I have owned the G1, myTouch 3G Slide and currently own the Vibrant. On each of the phones, I have not had the data plan with either phone. This is how:
First, I am on the Even More Plus Plan (No contract). I don't buy TMobile's subsidized phones. By not doing so, I am not locked in to their agreement to have the data plan. I have never had the data plan added at Tmobile's sole will. Whenever I call customer service about other issues, they will give me a hard sell about how you can't use your phone without the service. Ignore them.
Secondly, I am running data through wifi on the go with CLEAR, a wimax service. This device is a personal hotspot that travels with me and connects me to 4G (only works if you have Springt 4G in your area). In addition to my phone, it will connect up to 8 other devices (other wifi phones, laptop, desktop).
This benefits me because I only pay for ONE internet service and can use it at home and on-the-go. My wife and son use the same data when we are together at home and out and about. The good part is that I only pay about $40/month and the data travels with me for use and is sharable with up to 8 devices. I was able to discontinue home cable internet and t-mobile's data plans on 3 phones with the addition of this single device. Count the savings.
I have added the link for the device. It is called a
Clear Spot. By the way, I previously had Charter Cable Internet at 10mbps and the clear wimax service is much faster than the cable internet.