I had aftermarket ones for a while in mine as said above they do have separate plugs so you can fully disconnect the seat base.
I found that once I had sorted my heater out and had that working I no longer used the heated seats. They were never very good in my opinion (but that might have bene the kit I had fitted). Theoretically the kit had two heating elements and warm and a hot, but neither really did anything so I just wired them both together so both came on at the same time. A small improvement but still not properly warm. Not sure if the issues were the kit or the fact that I have seat covers and work trousers adding a couple of thick layers of fabric between me and the seat. I never bothered refitting them during the rebuild.
We have a freelander 2 and a 300 110 csw.
My partner uses the freelander, which is expensive to move about, expensive to fix, never works properly, and is generally hateful.
It is, however, comfortable.
Im attempting to jazz up the defender some, so as she will use that, and, ultimatly, the freelander can leave our lives, and, at that point, ill pass over the (now shiny) 110 to her, and get some ropey defender for myself.
She has heated seats in the freelander....
as a side note, re: heater -
im part way though a heater install thats triggered off the spare button on the central locking. the process so far has been -
crawl about under people carriers in scrap yards
buy broken units off fb market place
eventually end up with a couple of working units
think "it would be a good idea to use a central locking channel and a timed relay for this"
realise the central locking units need different door sub frames (*see note below)
when the subframes are bought, realise that the mount points need chopping off and moving on my old doors
then realise my winders are no longer any good with the new subframes
then realise my window fixing things are no longer any good with the new winders
and thats about as far as ive got - ive just finished blasting one of the frames, and ill probably drop it off for hot dip galvanising next week
so, on to "see note below" -
a friend wanted central locking. or rather wanted his central locking finished.
i kept telling him that the door sub frames needed changing. he kept telling me that it was possible to install on the old frames.
i assured him it wasnt, and you had to mount the actuator below, in some bodge it way, with bulders strapping etc.
he told me they mounted to the sub frames (the task that i couldnt do, and what caused me to swap all the sub frames over on mine)
...i told him id have to have a look at his, still not believing he had managed it.
"i didnt install them" he said, "you did, just before lockdown"
i have zero memory of the specifics of this, but i dont doubt him - and sure enough, they are on the old subframes and work fine.... i could have saved myself so much messing about on mine if id just done it the same way as (apparently) id done it previously....
(and, without all the messing about, i may have gotten the heater working by now!)