I.P. Daley doesn't talk about Cricket in the superguide because it's just a thinly veiled subsidiary of AT&T using reduced prices (and "lots of data") to lure people away from AT&T's actual MVNO competition. Might be a better deal, but your best bet is to figure out how to reduce your data usage and get on a more affordable plan with an MVNO like Airvoice.
+1. Did you always have access to high speed data? How did you survive without it? Do you have ready access to wifi most of the time?
I answered these questions as: I survived with no problems prior to getting my iPhone 3GS in 2009. I have wifi at home, and work - my 2 primary locations - and in-store wifi at coffee shops, restaurants, grocery, airports, etc. As a result, I went on the crash diet $10 pay-as-you-go plan from Airvoice (2-cent/text, 4-cent/min. calls, 6-cent/Mb data), and added $10 more when I needed it. The habit I changed was to switch OFF "cellular data" except when really needed (in the car/maps, etc). The first month I spent $15. Second month $9.50. Today I carry ~$20 credit most of the time.
Also, realize you don't have to stick with a plan forever - you can try one, then change plans next month, or switch to another carrier the following month.
I'm on Airvoice, and it says "4G" when cellular data is turned on (with LTE enabled).
With a T-Mobile (or AT&T) SIM in my phone, I see "LTE" in the same spot of the phone screen header.