Keep this in mind, and it does not matter the brand (this applies to all electronic devices)... one person can have no problems while the other person with the same model could have problems when you are try to increase performance.
Tan's firmware worked with no problems at 1.7 ghz (1.8 ghz caused it to reboot, 1.9 ghz could not even boot), bard's tail with the HD texture download, ran ok even on 1.4 ghz, great on 1.6 ghz and i really do not have to say anything on 1.7 ghz. yet other people with the same unit have it running on 1.8 ghz fully stable (not the best battery life, but they have no reboots... heck some people even had it on 1.9 with no real problems) Tan's firmware i thought was done very well.
currently i am using 'webclaw2-0131', i find that the battery lose on 1.7 ghz was to much and on 1.6 ghz it gives me the best battery to gaming performance. I will be honest i feel that webclaw's on 1.6 ghz feels more efficient than tan's on the same ghz. I like how tan's uses 5+ ghz for internal memory over Webclaw's 2 ghz, but overall i still think webclaws is better (if you are looking at 1.6 ghz)