Users have problems with the mods because they do not know what they are doing and do not take the time to properly read the guides. I have flashed all the mods and have had zero problems. Flashing a new rom is like getting a new phone, had i kept the stock rom i probably would have gotten rid of the phone by now. Don't let other peoples mistakes scare you from making your phone better.
I used the stock ROM for several months. 1/2 the fun for me was learning about how to install Clockworkrecovery and install Icarus 1.1, I had ZERO problems. Maybe a glitch here and there easy to fix, expecially with the forum to turn to.
THE BIGGEST POSITIVE of turning to icarus, The Ascend ha VERY LITTLE INTERNAL MEMORY. Icarus, runs Apps to SD A2sd by default, which instead of installing all your apps, etc on your phone, it puts them on the SD and puts a symbolic link on the phone (Shortcut) so your phone dosn't know the difference. You can also move the Dalvik over to the card with it (It's the go between engine for running the phone) you just need a class 4 card to be fast enough. Go get yourself a 4 or 8 (get the 8, why not), it should be class 4 don't even worry.
Instead of after you get going and have apps on it, instead of having 30 MB left, you will have 125mb left, and it will run 1000x better.
Right now I am running CM7 CyanoGenMod 7 , as I wanted to see what Gingerbread was like. I works well, has apps2sd built in, dosn't work as well as the other, but at least you can do it. I will admit, CM7 is a little quirky, but there are TONS of cool options. I'll probably play a while, then go back to Icarus.
Icarus 1.1 is definatly the best solid, no glitch ROM. BLows away stock, will make you happy w/ the phone..
Jeff