I have been using AIO for two months. I live in Texas and travel often. I just took a road trip to DC and had LTE/4g everywhere except some deep mountains valleys. I did byod with my iPhone 5 with the 40 plan. Minus tethering, AIO is as good as it gets. I have blown past my 250 MB limit with no noticeable effect. I still got full speeds, which with AIO is limited to 8 Mbps.
With my corporate discount, I was paying 76 a month with AT&T w/ unlimited data, 1000 messages, and 500 min. talk. Cancelled my contract and went to t-mobile with a corporate discount @ 42 a month with unlimited everything, high speed data throttled at 500 MB. T-mobile service was to spotty for my travels and I went hunting for another provider. Found AIO two weeks into their new business and loving it. My whole family is switching.
Could you PM me or share a screen shot here of the speed test? Do they fully lock you out at 4Mbps 4G and 8Mbps LTE?
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Thanks for clarification. Now the lines between AIO and GoPhone really are blurred for me.
GoPhone offers True 4G and LTE - VVM, International Texting, MMS etc
I'm on the $60 plan and have hit LTE speeds 30Mbps+ and everything works great...You can pay $54 for the $60 plan if you sign up for Callingmart and watch their facebook page - they offer 10% off coupon every month and that will give you:
True 4G + LTE:
- Unlimited Talk + Text (Including International Texting) + Unlimited MMS
- Visual Voicemail
- 2GB Data with 4G + LTE at full speeds
- Caller-ID
- No-Tethering and No Facetime over Cellular (Only thing you may get with AIO is Facetime over cellular - besides that its not worth it in my opinion) and Tethering will be possible again once Jailbreak for iOS 7 is out

So for that I don't see the need for AIO's crippled data speeds...probably because AT&T is trying to point consumers towards AIO brand where they give you less for same price as their GoPhone plans...would rather keep Post Paid customers on post paid and then have them look at AIO and see "slow speeds, half this half that" etc.
Some things to consider tho:
AT&T $40 GoPhone Plan < AIO $40 Plan (Wins due to Unlimited Minutes, 250MB vs 200MB)
AT&T $60 GoPhone Plan (GoPhone wins due to Unlimited International Texting, MMS, 2GB Full LTE Data & can be had for $54 from Callingmart.com w/ 10% off coupon) > AIO $55 Plan
AT&T GoPhone $60 plan can be purchased from Callingmart.com for $54 (Every month they have a limited time 10% off discount - use and load your phone - that money is already there for when your billing cycle starts.