I did the MTS .419 first and it was kinda buggy, so I used BBSAK to wipe my Tour and then installed Alltell's 419. Runs perfect. I would def recommend the BBSAK wipe first, whatever OS you choose.
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.419 hybrids are the best thing out right now, until .484 gets fine tuned. use any of the recent .419 hybrids and you will be blown away by the speed of the os and browser. very reliable also.