The MKV rips are more than adequate for me. In fact I usually go with 720P rips as they are usually 4.5-6GB in size.
Some guys can see the differnce, I do not have a 1080P TV though, I do have a $300 1920x1200 res monitor I use, but never tried a true 1080P rip to see if it makes any video quality difference.
90% of the stuff I watch on the HTPC is either TV (1080i anyway) or even anamorphic SD. So, I probably would not even notice true 1080P.
Aficionados though will tell you there is a difference.
Another consideration is converting hte BDRIPs to another format for storage yourself. Doing it yourself ensures full control over the results
