Let me share my experience using official froyo with my Samsung Galaxy S.
Before upgrade, I used 2.1 update 1 with OCLF 2+. So far I was very satisfied (run faster and very responsive). I backup all of my applications using Titanium Backup.
When upgrading, I forgot to uninstall OCLF. My phone become just black screen after upgrade reboot. I tried to go to Dev Mode reboot (Luckily it's still working) and just run factory reset. After reboot my phone is running froyo normally.
Official Froyo moment: I tried to rooted using OCLF and it's failed. I tried using z4root (Be carefull there is a fake application on the market) and successfully rooted my froyo. After that I successfully restored all of my paid application using Titanium Backup (I restore just the Apps). I feel froyo is not as responsive while I used Eclair with OCLF 2+. Especially the browsing experience (Probably this caused by Flash made it heavy load). I saw there were so many Media Scanner process every time you connect/reconnect to kiess, every time you reboot, every time install/uninstall apps, every time you do something with files (On Eclair the scan trigger is not so many as Froyo), and it's slowing you down. There is a new free app called NAVIGON (Good NavTeq application) when you upgrade the Official Froyo. Because of the lag, I install back OCLF 2+. It's help not much, and the lagging still appear but better while using OCLF 2+ installed. The flash is very impressive. I can played AQworld on browser, watching Anime Flash video, etc.
