I got my omnia about 2 months ago, and i was debating the same thing. i've been a palm os guy for a long time and still use my tx on a weekly basis. anyway, after finding this forum and with the help of many on here, i took the plunge the first time with the unoffcial rom, then when big A tossed his out of the oven, i went with base 1.0. things have been working great and i love tweaking this thing. there's still so much more to learn as it's not quite the way that i want it yet, but it's getting there.
i haven't been following 6.5 that much and i don't know if they're going to unlock the gps or not. but as mentioned above, you can't really go wrong if you follow the steps to flash your phone, and no one here is going to steer you wrong.
just my .02