FR's hybrids have the optional heated mattresses.
we use foam toppers and the heat still gets thru. not as strong as without the toppers, but it still gets thru. you just have to turn it up higher. but if you've got a 4"+ topper, it may not get thru much.
we would've not considered ordering it, since we rarely have electric hookups, but ours already had them when we bought it.
man, are we glad it did!
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC