Yes, many have. Try searching on "gel seat" and you'll see many threads including opinions about comparison to stock....and then inevitably lead to talk about many of the custom seat options that are far superior IMO. Or read my signature line on seat comparisons.
I have MamaYama's Gel (accessory) seat and think it's great. As a matter of fact, my much used Russell DayLong (w/'overload') now sits on the shelf.
I guess I'm just a gel-seat fan (works for me...)?
Years ago I converted my, then, dual-sport bike's seat (bought a kit -- gel insert & cover) and it was a wonderful conversion. Suddenly I could ride most of a day instead of just a couple hours w/some comfort.
After that I had a Suzuki S-T and when they offered an accessory Gel seat I ordered one. Again, a great improvement.
I have the gel and Russell. I only use the Russell for multi-day or 100+ mile trips. The gel works great for my commute and for some short weekend rides.
I had the Triumph gel seat on my Tiger and it was very comfortable after a slight bit of breaking in. There is one thing I found to be a problem with gel seats, however. If left in the Texas sun for any period of time they seem to hold the heat much longer than the foam type. :dribble: