Why are you limiting it to text messages?
Find a cross platform messaging service or just use GTalk. I find GTalk works very well and I tell people I prefer that they contact me that way instead of texting me. I can respond from my tablet, phone or computer.
I realize this isn't exactly what you are looking for, but a free Google Voice number could solve this. You can send and receive your texts anywhere, on pretty much any device capable of Google Talk or with a web browser.
I agree. Google Voice and Talkatone are both free and you can link your mobile number to your tablet. Pretty cool to make a phone call from your N7!!!!