Window motor replacement?

[n1ck73]

As it appears that the electric windows on most S series cars are, at best, rubbish, I wondered if anyone had tried replacing the motors or even the entire mechanism. I've tried everything I could possibly think of (and nicked from these forums) to sort mine but I still have to resort to pulling the window up by hand.
As there is a raft of motors/mechanisms on e-bay etc, has anyone tried fitting a more modern design?

[Gerald-TVR]

I believe the Griff motor will fit with suitable modifications (but i dont know what they are!!)