I was looking in to the solo Reach seat at my HD dealer, he told me the Reach wasn't much better then the stock for comfort. He said the Sundowner is the best, and I already knew that . I had that on my last bike. He said to get a Mustang for comfort on a solo seat. I can tell you for a 2-up seat the Sundowner is a good one, but not the best looking...
My wife has a 1200L and replaced the stock seat with the HD Reach seat to keep the low seat height. I sat on the original seat and then the Reach and was impressed at how much more padding there was. A 700 mile weekend trip proved the seat to be comfortable for her. I know the Mustang seats are excellent as I have a solo one on my Road Glide but, if you are inseamed challenged, the Mustang seat will probably be a little higher and wider. Given the cheap price of the Reach, I would try one of them first. Good luck!!
Just found this web site, when I googling " Reach Seat". I have one on my Dyna Low Rider because I'm only 5'2" with a 26" inseam. I needed the narrow front so I could reach the shifting peg and even with it, I was still standing on my tip toes at a stop. As for the seat, it's comfortable enough, but what I found really helps is the Kury Dually foot pegs with heel rests for those of you who have MID CONTROLS USING A REACH SEAT. It makes a world of difference as to how you sit on the seat believe it or not. I know there are more comfortable seats out there, but if you need your legs to be closer together and sit up closer to the tank, then you cant use those plush, gel seats. Anyway, the Reach seat works well for me, now that I got my Low Rider lowered ( progressive 430 shocks and progressive Front Fork Lowering springs) and the Dually pegs with stirrups.
I heard the reach seats aren't that comfortable and are surprisingly... well... they help you reach... meaning it is a very low seat and places you right up on the tank. About an hour ago I replaced my stock seat with the SideKick and I love it! Very comfortable, looks awesome... keeps that Sportster profile YET seats 2. I dont know how comfortable it will be for the looooooong rides but I wasn't going for that. I was going for something that wouldn't break the sportster profile yet could seat 2.