The Mercury II has a a better BLIND SEARCH capabilities than the Platinum. The MII gives the user more control of how fast or slow (detailed) the blind search needs to run.
Unless you have a need for a Common Interface Module, which th Platinum has, I would recommend the Mercury II.
Common Interface Module: Will allow you to insert a Conditional Access Module (CAM) and smartcard for subscription purposes. Mostly used in Europe, Middle East, or S America.
I have the Mercury II and it's a fine receiver great picture quality when hooked up with the component cables and the blind scan does a decent job misses a TP every now and then but seems like they all do.
i love the mercury as well . i have a classic na as well.but when it comes to finding a sattelite the mercury got my vote .i spent the better part of a week wit the clasic na coulden find anything but i was only a hour with the merc found 3 sats ! of course the signal beeper was of an great help.now if i could get g10r.
the na is not a bad ird but its as not as good as the mercury11 just my 00.2cents.