Preferred heating for racks?

[mainbutter]

I am currently working on switching all my racks to back heat now.

Do you have any CB-70 or similarly large-tub racks?

What is your room temperature that you keep the racks in?

I'm going to be in the same boat of needing to decide heating type, but I often have room temps in the mid to high 60s, and I'll be using larger tubs that may not heat well with back heat.