I still have an aircard through Sprint, and cannot use it half the time thanks to the 3G being way over crowded here in Phoenix, but it's sure nice to use when i'm in a WiMax area (i will buy a TriFi when they finally get LTE here in Phoenix)
I can say though as an S&R Tech here in Phoenix, i do see a lot of phones that i have to send back to the customer because it's rooted (95% of the time has some free tethering app installed) and i cannot work on it unless they get it back to stock.
I can say it's a chronic issue here in this market, and the 3G performance shows it. now, i cannot speak if tethering is the issue, but it cannot be helping either. I just hope the NV upgrades come soon as they cannot come fast enough.
You would be amazed to see how much capacity is actually at a cell site, and just the sheer volume of data hits it's getting throughout the day. Trust me when i say there's plenty of capacity, but in markets like Phoenix, it's just a matter of way too many subs in a given area at a given time, LTE should help as well as Nextel refarm, since it's separate bandwidth from what's currently being used, but only time will tell.