Living in the Midwest I can say that Thor's heater mod switch was really helpful to me. With it, it allows me to chose when to allow heat or not(or even reduced heat), something that without the switch the only way to control the heat most of the time is turning off or on the climate control, something that generally doesn't work well due to window fogging. Even with the switch the my '12 heater seems to not work nearly as well as my '13S(still resistive heater but no water/antifreeze to slow the process down and as mentioned by Leftie Biker I believe the '13's and on have more/better insulation).
I guess if you could get the '12SL with the new battery(I'm envious of you) and it was several thousand dollars less than a '13(even a S) it might be worth it to you. As for the range, on my '13 on the most bitter days my range was ~40 miles with mild heater use, 32 would be totally doable but it would be a must for you to charge at work. Note since the '12 has only a 3.6kwh charger, expect only about 15%/hr or a bit or about 6+ hrs from near empty. A '13 with 6.6kwh charger would be under 4hrs with a 27.5a max EVSE, a bit over 5hrs charging at 20a.
If you get a "S" model make sure it has the 6.6kwh charger. Most sold in the Midwest had that option, not sure about Southern cars....
If you get the '12 figure on spending a little on the heater mod switch as well as LeafSpy or if you want to try and track down something like LeafDD or similar permanent type gauges.
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a