Buying a GS3 Now?

I'll keep this short.:

1) I am staying on AT&T (reasons below if you must know)

- VZW coverage is non-existant in areas that I freqent

- Family plan

- Grandfathered "unlimited" (not important to me as it's throttled)

2) I am eligable for upgrade pricing and am fine with being on contract (see #1)

3) I need LTE (my city has great LTE coverage and terrible 3G - I frequently get less than 1Mbps down). My coworkers on AT&T LTE regularly average 15-20Mbps+

4) I am definitely willing to run CM10, etc. to attain a "stock" experience

Am I making a bad decision to grab a GS3 for ~$100 and run an aftermarket ROM for a "stock" Jellybean experience? I would be totally fine with using this phone until next year's Nexus is released (which hopefully has LTE), and buying that one for full price.