Both these route your texts through the net, so instead of your number, what shows up is just a bunch if wierd numbers, and your name,people can reply to them and stuff but it just wont be your number
I tried text+ before they had push notifications and its kinda decent, i really didn't use it long enough to really have much of an opinion, its not bad, just that it has ads which is really not that big of a deal considering.
Textfree I purchased because ATT charges way too much for text, again i originally bought it before push notifications, and it was perfect. but after the new version, I think I may end up using trying text+ again. A few things about it really irk me, I paid 5 bucks for a damn app that spams me with its products every so often when i start up (not a big deal, just an inconvenience), I can't disable auto rotate (also not a big deal). The big deal is that it takes forever to load, and when it does load it'll crash and bring you back to the springboard every few times, not only that but it feels like it store your texts on its server, just because everytime you open a contact it takes forever as well, I've read sites that say that textfree is the best text app so far, all i know is it frustrates me. I have a jailbroken 3g, so maybe its a jailbreaking issue? i dunno... thats just my opinion, i suggest trying both since text+ is free and there's a lite version of textfree