I contacted Nextel about a Mil 810F/Rugged Phone such as your listed i58 or i88. They said they have been phased out and recomended the i355 or others which appear to be Java capable per their new POSITIONBRO _5/05 yellow brochure.
Will this phone work since it's not on your recommended list?
I haven't yet tried Accutracking on a i355, but I should have that opportunity by the end of the week. I do run it on an i325. From what I can gather, the 355 is very similar to the 325 with the exception that it is not rated "Intrinsically Safe", it has a retractable antenna and a larger display. On yeah, it's a whole lot cheaper.
I've loaded the i710 version onto a i355 and it is working just fine. If you don't need the IS capability of the i325 IS, then the i355 is definitely the way to go. Much nicer display (big and bright), backlit keys, retractable antenna. Nice phone.