Interesting, thanks all.
Mine is a Sky-Watcher 200P. The slewing was a bit snatchy with the standard teflon setup, hence why I was looking to upgrade. I tried 5 individual bearings first but they were really poor quality and sounded like they were made from gravel, even after greasing. I removed them this morning and cleaned everything, again. Back to the original setup and it doesn't seem so bad, compared to the bearings I've removed - I'm sure I'll get fed up with it again though.
The bearing company I spoke to suggested using slewing bearings, which look similar to the type 1 ring bearings, above, however, unlike the type 1 they were prohibitively expensive. I've found a 506mm diameter slewing ring in Germany, for £60 inc. postage, which is still a lot and would cost even more to return if I didn't find it suitable. The base diameter is 520mm.
With the lazy Susan or slewing ring bearing potentially moving too freely and requiring additional friction, I'm concerned that I'll end up losing the smoothness of movement by inadvertently re-adding the snatchy feel.
Not sure which way to go from here.