Hello from California,
I have a Vendetta, a Quest, and a S30, purchased in that order. I use the Quest for commuting, but because most of my miles are on the V and the S, I have at times wished for a frame like those two, but a little more upright and with rack mounts. Then along came the S40. While I do enjoy the Quest, my thinking has been that if I could sell it whole for about what the S40 frame kit costs, I would probably do it. Then along came your post.
I have upgraded this Quest. I replaced the squeaky, boat anchor rear shock (which still comes on the current Q model), with a much lighter and more supple/adjustable air shock. The chunky, low-end wheels are now zippy-but-still-strong hoops built around WTB hubs and rims (I build all my own wheels, and this was the first change I made). The original budget- level persnickity 2x9 drivetrain is now a smooth and precise SRAM 1x10 setup (my commute is flat, and the 10 speed cassette has a wide enough range to make a front derailleur unnecessary). And the original seat pad is now a Ventisit pad--a definite upgrade. I believe that these upgrades have made a noticeable performance difference over the stock Q bike. It doesn't match the performance of my V or S, but it is definitely a smoother, more comfortable ride. I am the second owner, and while this bike came with the some minor cosmetic knicks and scapes that I call normal for a commuter, the bike is in excellent mechanical condition, I have maintained it regularly, and I don't ride it in the rain.
The S40 frame kit is $2300.00. If that price range, plus perhaps a little more to offset at least some of the shipping cost, sounds too rich, feel free to say, "thanks anyway." But if that price is not prohibitive, and what I describe above piques your curiosity, let me know and I will take and send pictures.
Have a great day,
Craig