It is true that it will install most apps and you will probably have to reinstall some apps. But it is HIGHLY recommended to wipe data and cache. This is why, remember the old froyo maps install did not work. This froyo maps will install, to get a clean install and keep from having to do it again later, just wipe data and cache. I personally did the 3 wipes that was suggested when the first froyo was leaked (wipe data and cache twice b4 install, and once afterwards.
also after installing froyo and getting your stable kernel....make a backup (nandroid backup) immediately.