Howdy --- hope this is not too redundant, but just to make sure you covered all bases in a conservative way ----
(1) Hope you made a Nandroid image of your previous install. Always nice to have to fall back on.
(2) I learned it is best to upgrade to RA-1.6.2 from RA-1.5.2. Several reasons but the "6" version has some important fixes in it for working with 2.1 ROMs especially when moving from 1.5 to 2.1. I would do this if you have not already. Just replace the older version on your SD card before doing your flash procedure.
(3) When you boot into RA-1.6.2, the WIPES ARE CRITICAL. And in your case where it sounds like you already partitioned your SD card to use apps2sd. You MUST wipe the DATA cache, the Davlik cache AND the EXT partition. All three. Some even prefer at this point to convert their EXT partition to EXT3 to get the benefits of journaling for partition integrity.
(4) Now you are ready to flash the ROM zip file. When done, immediately reboot, and give the Hero plenty of time to boot and configure itself. Wait for the HOME screen before doing anything with it.
What I have outlined is a conservative but thorough approach to 2.1 ROM flash. Hope this helps to maybe catch something you forgot in the procedure.
Good Luck -- Bob ---