a few dyno test I've done, has showed that the Non MDS cam made the same Peak HP and TQ #s as the MDS cam, but the Non MDS cam had a better average HP and TQ by almost 15Hp and 20ft tq, from about 2500-4000 but only you can decide if that's worth the $1??.00 price difference in cam and not to mention the price between the lifter types.

I've seen the cam drift back or retard it's self under high rpm and oil pressure when the VVT is unplugged and the solenoid is left in, not sure what caused it just haven't had the time to figure it out.
best bet just plug it if your not going to use it.

http://www.stankemotorsports.com/services/index.htm