There was a Saniflow loo already fitted in a house I once owned.

Overall it worked very well and it was a useful bonus having 2 loo's in the
house.

As the other poster noted they do not cope well with heavy waste, IE sanitry
towels etc. But normal waste and loo roll are find. In the 3 years we where
there the only time I had a problem was when one of the kids decided to fill
with the pan with unravelled loo roll and flush it! That was an unpleasent
job to sort out.

They do make a bit of a noise when the loo is flushed as the maserator does
it's job but only lasts a few seconds and is not that loud..

Used sensibly I think they are worth it to have the extra loo.

Eric.