I am known to be a bit of a ibis ti nut.. love them and have three. one of these is the bowTi. 5 inches of travel, no mechanical pivots, scrummy.
I confess I havent ridden a Silk Ti but I have heard they initially feel like a soft rear tire if you come from a hardtail. but that you then get used to this and enjoy the cushioned ride. The ibis ti frames are all works of art, stunning. I know the one on ebay, its been listed a while but its a pretty rare an unusual frame to sell and the guy selling knows what it is. Think he has a bowTi also.
If I didnt have my bowTi I would be looking to buy one like the one on ebay.
oh and if you want a disk mount adding, steve potts is yer man.