Luckily I've got a CAT aircard which is working awesome. I can Download at a reasonable speed and I've only had one D/C whilst grinding in 2 weeks. I definitely recommend one of those to anyone who is thinking of getting one.
You have to be careful with recommending this, as not everywhere has access to EV-DO, and your experience in Chiang Mai might be completely different than if you tried using it everywhere else.
From what I can gather the CAT aircards work fine in CM, Isaan, some parts of Phuket and Pattaya, they don't work at all in Bangkok and only get regular CDMA speeds in Samui.
So your mileage may vary, pays to check with other people in the same area who are using EV-DO first.