I friend of myne owns a monster 1000s.
The bike handles great, alot more fun on the road than my mille. The gearbox is smoth and precise, at low speed better(a lot) then the clunky rsvs, engine pulls strong and steady, revs fast, but dont know if something is wrong or its just a ducati feature, when the rev limiter kicked in for the first time I almost **** myself, it was like someone just braked hard for you. Brakes by the way are also great. Comfortable, but above 200kmh on the highway the comfort stops.
Cant realy say anything bad about it except the pegs could be higher for track activities
Reliability wise its about the same as with aprilia, it all depends on your luck
He had an engine failure, some bearing was defected or something, after the repair the bike now runs fine. Nothing more to service than an everage bike, just it needs the valve checking in service intervalvs and you have to change the belts.
But I wouldnt go bellow 1000cc, heard that even monster 900 is a weak thing.