Thanks for sharing your experience B.A.T.! That is essentially what I'm doing, except getting my wifi from a dedicated mobile hotspot instead of an ipad...but I didn't know you could by default use the ipad's data as a hotspot, that's pretty cool...
I also had a brainstorm - I think I'm going to trade my ipod touch in for an iphone 4, but still use it the same way, as a GV data phone - I can get a used iphone 4 for the same price as a new ipod touch - and the iphone 4 has more RAM, better camera, and perhaps most significantly - I can use it as a normal phone with GV instead of HAVING to use a headset (i.e. I can hold it to my ear and use it in the traditional old fashioned phone way). Epic win. ALSO - by using an iphone instead of an ipod touch, I can get a prepaid pay-as-you-go ATT SIM card and put it right in the iphone instead of lugging around a separate 'emergency' phone...for those few rare instances where I don't have data, I can use the pay-as-you-go SIM for phone calls, so I won't be stranded.
Funny, this all started because I'm an "apple" guy, have been using macs as primary computer for many years. But never had an iphone/ipad, always been using Android since the smartphone craze warmed up. Probably because I've been with Tmobile for a long time. But I've felt the itch grow strong recently to go Apple in my mobile life as well as home. So I got a new iPad, liked it, but still didn't feel complete, with my dependance on the Android phone. the iPad just felt like a novelty, since I had the smartphone already. Anyway, started thinking and reading online, and I realized that this was the best option for me to actually save money, and fulfill my desire of having a mobile Apple computing platform. As far as I can see, the ipod touch/iphone can do everything the ipad can, just with a smaller screen. For me, it's perfect. All my major work will be done on my imac at home - the mobile solution is just for keeping connected and messing around/light work. By returning the iPad, and going the GV/no phone plan route with an ipod touch/iphone, I'm saving a buttload and will have a fully functioning iphone, which in the end, is what I really wanted. TBH, not much I can do with ipod touch/iphone that I couldn't do with my android - but I have been longing to have unity in my computing/digital life, what with the mac at home...plus I love apple apps, and the polish on the UI. Google/android works, but Apple works and makes it look good. Add to all these incentives the fact that I'll be paying HALF my former phone bill, and won't be locked in to a contract, and I'm sold.
Lol sorry for long winded post, just excited to be on this path!
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Oh and p.s. one last thing I forgot to say - it's more that a few hundred bucks over 2 years. For me, I'll be paying $50/month for unlimited 4g. In 2 years, that'll come to $1,200. The typical Android/iphone plan is in the $90-110 range, let's just say $100 even for argument's sake. So 2 years of that service comes to $2,400. In your case, at $30/month, it would come to only $720! That's a savings of $1,700 over 2 years for you...nothing to sneeze at.