From what I have read you can get HSPA+ but not LTE when using the AT&T SIM on straight talk with the verizon note 2. Also in 4.3 there is no need to root to update the APN. Otherwise it works fine.
I was thinking about switching but after doing the math my verizon ETF eats all but $40 of the savings over the next 8 months until my contract ends. Will check it out again come September.