Ok lets see where to start. I would guess a P7 throws a bit farther than a MC-E but alot depends on the bin. The newer Mbins brings the MC-E very close in throw.
Total lumen output I really could not tell you, I can quote figures that all know but that is it. They use a small reflector so it will not be like a mag but still very bright.
By 16x or 17x I take it to mean 18650 & 17670 or so. Either of these will run this fine. Two cr123 also do great. I can wire it 2s2p but it will take at least 6.4 to 7.2 volts to work since you add voltage and reduce current. One batt. will not function on 2s2p 2 full power.
when it comes to losing throw, this is hard to say, yes the R2 may throw a bit farther but will there be enough light to see what you need to. That is where the P7 & MC-E come into play what they don't have in throw they more than make up in volume. I think you would be pleased and have a hard time telling the difference as far as throw goes, now volume you can tell (300lumen VS 800 lumen)
Here are some wall shots @ about 9 or 10 feet. It was not night but still visible.
Smooth reflector P7
Smooth reflector Warm White MC-E
MOP reflector Warm White MC-E
Here is one with a cool white R2 against a K2TFFC warm white
Well there they are hope it helps.
Thanks
Dave