Do be aware that in order to use the data available on the Omni (at least in the U.S., and maybe elsewhere- I am not sure) you must upgrade to the 3G Omni-C. The original Omni uses 2G, whose frequencies the FCC reassigned for some other communication. It doesn't work for cell connectivity.
What kinds of conditions wrecked the previous ones? I do have a screen protector on mine, but I ride in the ran all the time. If they leak easily I'd like to know. I never had any problems with my original, and I haven't had any problem since I swapped it out for the Omni-C. There is a nut on the bottom of the unit where the on/ off button is located that needs to be snug for a good seal. Maybe yours was loose? That's concerning though. Good luck.