I follow the thoughts of Vince Marinaro..."one reel for everything". I'm going to qualify this for fresh water, salt water I'd do the same thing but a more suitable reel.
My current system is the Orvis Clearwater IV for fresh water. I have them loaded with lines 4 thru 9 with some of the lines on extra spools.The Clearwater reel has a standard arbor. I don't see the advantage of bigger arbors, it just reduces capacity, and when you fill up the standard arbor with backing to the mid or large arbor capacity you get more backing for the buck and the flyline coil is the same.
I paid $39 bucks for the reels and I own 3. I bought 4 spools at $12 bucks apiece. Orvis spooled without question, 20 lb. dacron backing on all of them without cost. My cost for this was $165.
It's just the way I look at things and have nothing against a high dollar reel. I love 'em and would use the same approach for a high dollar set if I had the extra bucks. By comparison here is the difference : 3 Orvis Clearwater Reels @ $39 = $117
4 spools = 48
$165 = 7 lines with backing
1 Orvis Mid Arbor V =$169
1 Spool = 89
$177 reel + spool 2 lines
I can have problems with any part of my deal but I can switch parts and pieces and be in business. It's a lifetime setup for me.
Before the Clearwaters I had and still have 2 Berkley 1056 with 2 extra spools. These were all set to fish a 6 weight line.
"As far down the river as he could see, the trout were rising, making circles on the surface of the water, as though it were starting to rain."- E.H., The Big Two Hearted River