What are the advantages or disadvantages to both? Or, what makes one better than the other?
Hello 13111, I wonder if you’re asking from a rod building perspective
or from a user’s point of view ?
Cheers,
MontanaMoose
User’s. Its more out of curiosity
…well to me it seems like double foot are better and you’ll hear
pros and cons on that…they say if one wants to slow a rod down some,
single foot guides will do it…they sure look ‘cleaner’ on the same blank
that comes factory with regular snakes.
Conversely, a factory rod with singles could conceivably be made a little
‘faster’ by putting doubles on instead. Again all debateable and I know
once they’re out of bed the builders will add to this terry13111 !
Cheers,
MontanaMoose
I’d love to attack this one LOL… but,… let me just say singles look great on spinnin’ rods.
From a mechanical POV, snake guides allow the end of the leader/beginning of the line and the end of the line/beginning of the backing to go through smoother than with regular rings. Regular rings are designed to allow mono/braided line to flow through with minimal fuss, but make it harder for knots to go through.
Jim
Disclaimers first…1) I build my own rods, but I’m miles away from being an authority…2) I love to flyfish, but I’m also miles away from being an authority.
So with a grain of salt, I’ll say that unless you are capable of riding the fine, far edge of your equipments capabilities, you will probably never notice a real difference in performance between the two. I use both, and it boils down to the aesthetics of the rod I’m building at the time.
Of course, if you put single foot guides on bamboo, you are probably a dangerous, kitten-kickin’ commie. I’m just sayin’. 
I read this someplace but cannot remember where:
Rod flexes less in the space between wraps on double footed guides then the rest of the rod. Sigle foot gudies allow the blank to flex almost unimpeded.This could be a good thing or bad think depending on the design and use of the rod so it’s more of the builder\designer thing - but really personally I think the difference is minimal. To me single foot gudies are just more esteticlally pleasing…
Single foots cause the rod to be somewhat lighter. Although both weigh about the same singles only require 1/2 the thread and finish.
In my rod building days I used both. I found singles to be harder to wrap. And (perhaps mistakenly) singles did not “look” quite as substantial. As time passed I decided I liked to look and the traditional double foot snake. All of my recent acquisitions have had double foot snakes.
All the pros and cons mentioned above by others plus some users prefer snake guides as the are less likely to be bent while bushwacking. LAlso like others, i find little difference in everyday performance. As a hobbist rod builder, I use single foot guides on most rods in the 2 - 6 wt range and snake guides on higher weight rods as they are geared to larger fish and tougher treatment.
Dr Bob
I got into the ‘technicalities’ of fly rod building pretty heavy a decade or so ago.
ALL of the fly rods I actually use have single foot ceramic insert guides on them (EVEN my cane rods…I’m not nostalgic…rods all work just fine).
Why?
Better ‘everything’ as far as weight/performance/durability goes.
Will the average, or even the expert, fly fisherman notice a difference while fishing? Doubt it.
I used them because they were best available product for the job.
Here’s ‘why’:
They are several magnitudes ‘stronger’ than bent wire guides. Titanium framed SIC guides are incredibly strong and light weight…they will last centruries. The smoother ceramic inserts also contribute to fly line life…I’ve never ‘worn out’ a fly line and I know guys with wire guides that have…I have broken or damaged them by being careless or unlucky, though.
The top end ceramic insert guides weigh LESS than similar sized plated wire guides (titanium wire guides are lighter, though).
Why single foots? The ‘single’ wrap saves a lot of weight…most guides wraps and attendant epoxy finish weigh MORE than the guides that they are holding on the rod.
Weight, especially near the tip of a fly rod, is the single most negative factor that effects pure blank perforamnce. Anything that you can do to lessen weight will make the rod perform better…will the fisherman be able to ‘tell’. Nope, but it’s still ‘there’, whether or not you can tell it is. It can add up, though…a bit less fatigue over a long few days casting…a bit longer ‘average’ cast…a bit less effort for the same distance, things like that ‘add up’ even if you can’t 'feel it.
When I built a rod, I used as little thread wraps to hold the guide as possible…I used only enough ‘finish’ to seal and cover the thread…I used as few guides as possible without sacrificing blank support (hardest thing to do, technically, on a quality fly rod blank…why the best custom builders get the big bucks). All to keep the weight to a minimum.
Can I ‘tell’ the difference in casting the rod…not really…but doing it the ‘best’ way possible was what I wanted to do, not just ‘copy’ existing old techniques.
Rod builders and the companies that make components have progressed far past the ‘cutting edge’ I played on a decade ago…threadless guide attachements…even lighter, stronger guides…blanks that weigh less with the same strength and power…some guys are building true cutting edge rods that are far superior to anything produced in a factory…
Yet, it’s still just a fly rod. Old fashioned wire snake guides still work just fine, and many prefer them not because they are ‘better’ but just because they look ‘right’ to them.
I do know the fish certainly don’t care.
Buddy
I have rods with both and notice very little difference. Since they are on different weights and manufacturers, it is hard to compare. I have built rods with both and found that the single foots are quicker to wrap, but harder to make the fine-tuning final line up.
The snake guides have the clear edge in the winter. Less icing up.
Just remember, you can’t have too many rods! 
Rex
I give a strong second to that one. I didn’t think about it when I read the question, but it is definitely true.