I was just trying to update my Facebook and then also thought about trying Firefox 7 but both are saying they are not compatible. I think I must have done datatoext since I partitioned my sd card from 3 to 4? I feel like an idiot for not knowing how to fix this. I've never had any problems with Reborn and updating apps in the market.
Mine only stays downgraded for a short time. After anywhere between 1hour to 2 days it auto updates to the new market. No biggie but new market is sloooow...and data intensive compared to the old one.
anywho...FireFox only runs on arm7 and better, so it really is not compatable with our ARM6 Optis...
ARMv6 (experimental)
Sorry, the experimental ARMv6 builds are no longer available. They contained bugs that caused them to crash immediately, so they were no longer useful for testing.
While we'd like Firefox to run on as many phones as possible, we are focusing first on devices that can run current versions of Firefox with acceptable performance. As we improve Firefox's speed and memory use, it might become possible for us to support ARMv6 phones in the future, but we are not actively working on it now.
Source:
https://wiki.mozilla.org/Mobile/Platforms/Android#ARMv6_.28experimental.29