4Ω speakers are really dependant on your choice of amplification. Personally, I like 8Ω speakers because most of the time you do not have to worry about what you choose to drive them with, any modern amplifier will run 8Ω with no problem.
Pioneer elite should have zero issues running 4Ω speakers, but If i were given a choice between two identical Paradigm speakers with the only difference being the impedance, I would nearly always go with 8 ohms.
The reason i asked about 4&8ohms is bcuz I have 12 6x9s that I had bout the mdf pre-fab boxes that I have set up at 11.2 that sound great!
Ill put it up against anyone's system... And I only spent $200
The SC-65 is rated for use with 4 ohm loads by pioneer.
My only suggestion, would be, that you look for a "setting" somewhere related to the impedance. Some receivers have the option to select 4 ohm or 6+ohm speaker settings. The lower impedance setting on some units *may* adjust the feedback loop on the amplifier to better suit the expected zminimums. (cause less dip in response at zmins). It's sort of a moot consideration since everything is probably EQed through a management package like Audyssey anyway but it's something to look for.
EQ these days can solve just about anything, even car speakers in the living room I imagine it sounds very pleasing.