Thanks for the advice I think we'll give it a go. We've been worried about the dust and tracking with the wood base stuff for a while and everything i've heard about WB litter seems to indicate that's not such a problem with it.
We have 9 adults ATM - snow marbled stud boy, 3 entire girls (1 brown marbled, 2 brown spotted) and 5 neuters. Also 6 brown marbled kittens currently 11 weeks.
We did have 10 adults until last weekend but have just rehomed an older neutered boy and will be rehoming 2 more neuters when we find the right people for them. We've realised 6 or 7 adults should be the maximum as it's selfish IMO to keep more. We found that however hard you try it's impossible (again IMO) to give a larger number of cats especially bengals the individual love and attention they need to be truly happy. Whilst perfectly content the boys were getting bored and overeating and heartbreaking as it's been we had to act. More than a few tears in the car after dropping him off last saturday.
Needless to say we don't use pens and cages and the cats live indoors (with outside exercise runs). Hence the litter issue. No disrespect intended to those keeping lots of cats in specialised housing but it's not our thing.
Re bengals leaving presents I was in bed yesterday morning (work nights) and heard this odd light beating noise against the closed door. Further investigation revealed the source: queen outside door peeing at it to attract attention of stud boy asleep on the bed with me. He slept on oblivious. I got the Simple Solution out.