Here is my 2 cents. I upgraded my Curve 8330 to OS 5.0 from Boost yesterday. I did the delete vendor.xml and ran Loader.exe, as recommended in the CrackBerry article. I took a long time and ran fine. The 8330 does not have a lot of memory, and the 5.0 uses about 10 mB or more memory than the 4.5. Also, Blackberry Maps does not work (I've heard that it is because Boost does not have it on their BBs), which is no big deal for me since I use VZNavigator. Memory became the big issue for me, even after deleting some unused apps. This morning I had the bright idea to reinstall OS 5.0 using BlackBerry Master Control Program (http://mcpfx.com) which allows you to NOT install some core items like default themes, VAD, BBIM, and some other programs. In all I saved 15 mB in not loading those core apps I don't need and brought my free memory up to an acceptable limit. Remember to back up your phone using the Desktop Manager & Master Control Program (third party apps). You must leave the Dimension ZEN theme installed for any themes to work, but get rid of the rest. As for 5.0, the default browser is extremely fast, I was able to get rid of Bolt & Opera Mini browser. It also has memory compression which allows you to operate with less free memory (I think). I really like 5.0 so far. It is a big improvement over 4.5 both in features and speed.