OK. I got my Sargent and just did a 100+mile group ride to break it in. Here are my impressions.
As you may all know, the build quality on this seat is FAR superior than the stock seat. I was actually in a mild state of shock to witness the difference. The amount of detail you see in this seat is just amazing. The best features of this seat I believe are hidden underneath.
The clear plastic tube container has the capacity similar to the stock seat case. The tube detaches easily just by releasing the rubber loop that holds it down. No unscrewing necessary. I will actually be using the storage space more often now. The tube is somewhat air-tight and I can imagine getting decent protection against humidity.
The bungee hooks are also a great feature. The hooks stay in place by friction and they won't loosen up and start rattling. Although I haven't used them, it's nice to know it's there.
The seat sits on the frame on top of quarter-sized rubber mounts that damper vibration. I think the mounts do a pretty good job.
The stock seat fender screws on to the Sargent with no problems. The fit is perfect.
One glitch (and it could be just mine) was the fit against the tank. It doesn't line up to the tank like the stock seat. The small gap does bother me a little, but not too much. It may get better in time after it's broken in.
Now for the comfort issue...
At first, I was rather disappointed with the seat. I can second what Scott S. and kevdusmc wrote. The stock seat does give you a better "hold" of the bike. The front of the Sargent is a bit wider than stock. It also puts you a little higher than the stock position. This prevented me from hugging the tank with my knees like I used to. I did feel kinda loose sitting on the bike.
Another thing. The seat dips towards the rear. This creates an angle that doesn't naturally push you towards the tank. On acceleration, I have to make extra effort to hug the tank and grip the bars so the momentum doesn't send me sliding back. There is the little "butt support" but I am too short for it to be of any real support. I guess if you are taller than 6ft, it just might serve you good.
However, the comfort level is much better on long runs. If I did the same intense 100+mile canyon ride with the stock seat, I wouldn't be walking home with absolutely no pain. Amazing but true. This may be due to the foam they use or the rubber mounts that are in place. I also think my butt has managed to mold the seat into something better fitting - or maybe I just got used to it. Now I don't get that odd feeling like when I first sat on the Sargent. It's probably still breaking in.
The seat is not perfect, for me at least, but it is an acceptable product. I will keep it. ;D
