When using home made connections that allow the removal and replacement of the sink tip it is difficult to get a connection that will go through the guides smoothly. For the best casting properties you want the tip to be looped directly to the fly line without the mono. I use braided loops for this and construct my own as shown here : www.danblanton.com/gettinglooped.html . However these still can get hung up just as similar loops on older versions of multi-tip lines did. You can also buy braided loops but I find most commercially available loops to be not as strong and durable as the ones I make. I find it works much better to have the entire tip outside of the guides, but has you have observed, this can get inconvenient as the tip gets longer.

A mono section between the line an tip is workable for short tip lengths of 1' or 2' or so. . I think the best way to do this is to nail knot a short section, 3" to 6", of heavy mono to the fly line as a leader butt and put a loop in the end of this leader butt. Use 30 or 40lb test line, or cut a section from the butt of a tapered leader (even a used one). This works but the thin mono between the two thicker pieces of fly line can lead to some funky casting.

The new versions of the multi-tip lines have welded loops and these go through the guides much better. I was given newer version of a Rio Versatip line a few years ago. These lines have interchangeable 15ft tips and welded loop. I had minimal issues with the loops going through the guides. But I don't know of a way create equivalent welded loops myself. Scientific Anglers sells 30ft sections of their T10, T12, and T14 lines with a welded loop in each end. These can be cut, giving you two sections with a loop on one end. If cut into more than two you will have two sections with and end loop and one or more sections with no loops. Many of the line makers now offer lines with welded loops in the end. One of these looped sinking sections, when connected to the built in welded loop of a fly line, may go through the guides much better like with the Rio Versitip line, but I have not had an opportunity to try this myself yet.

Any time you start adding a heavy and dense sinktip to the end of a factory fly line, or even add a floating section, it will start to effect your casting adversely. The taper on a a fly line is designed to turn over a leader and flies of the size and bulk that might normally be carried with the line. Flylines weren't designed to turn over and add on sink tip. It works reasonably well for short tips but gets more difficult as the tip gets longer. Add a long leader to that and things can really get interesting. I used to use 6' add on sink tips quite often and usually kept my total leader length in the 3'-6' range. I bought them (Orvis) or made them by cutting off line from the back end of different density full sink lines. For me, I found that if I started going beyond about 6-8 feet of add on sink tip I just didn't like the casting properties. I have used add on tips up to 15' but had to do lob casts and still have the connection outside the tip top. Interesting thing was that If I used 25-30 feet of add on sink tip the system would cast better and work like a shooting head system, but not as well.

Another thought on the leader is that you can sometimes do yourself a disservice by using a long leader with a sinking line. The length of the leader you can use effectively will depend on the sink rate of the fly, the leader material, and the sink rate of the fly line. If your fly doesn't sink fast enough, the end of the fly line will sink below the level of the fly and you will have a belly in the leader that impairs strike detection. Even heavily weighted flies, especially if made of bulky or buoyant materials may not sink as fast as we think, compared to the sinking fly line. I discovered this many years ago when fishing some large heavily weighted clouser minnows with a leadcore shooting head around the local kelp beds. These flies would really hurt if they hit a person on the cast. I was using an 8ft leader. The sun popped out of the clouds and the water was very clear that day. Visibility was more than 25ft. I had made a short cast to a close by kelp stringer and watched my line and fly sink. By the time the end of the flyline was about 15ft down the fly was only about 10ft down. I shortened my leader to 3ft and started catching fish.

The use of add on sink tips is a compromise between performance and functionality. It provides some versatility without having to carry multiple outfits. I use them when I need to go with minimal gear and prefer the factory multi-tip lines, or better yet multiple rigs. There is, of course a cost factor with muti tip lines, which cost as much as an inexpensive rod and reel, as with multiple rod/line setups. I usually carry multiple rods myself keep the extra or extras handy and rigged up in Dan Blanton's Rigged and Ready Rod bags, one of which I have even modified with a sling to carry on my back. But If going really light, I still carry a set of 4 sink tips. In my cast I have 4 5' tips of different densities to get different sink rates.