Once again, there's no 4.1 for classics. You can't use 4.1. You can only use 4.0, which you can buy from your favorite retailer.
As for the experience, I don't know, I have a CyberstormPPC+CyberVision setup, I bought and installed 4.0 just for the sake of it, but I still use my ClassicWB setup mostly. 4.0 don't have drivers for my X-Surf ethernet board, (you need to do some tricks to use 68k drivers I believe which I didn't bother) and generally some pain to setup properly. Your mileage may vary though. Check youtube for some videos to see how it looks like.