Your post intrigued me as I didn't know Benchmark was using better connectors. I moved my crossovers external and used speakon connectors from the crossover to the speaker. I agree they are superior.
I then looked at the Benchmark power cord. The locking plastic tabs on the power cord are not a bad idea. but to add a 50c piece of plastic and try to say it makes a 14 awg cord adequate doesn't cut it for me.
So if there isn't room for an upgraded power cord I'd say benchmark screwed up pretty bad.
Audioquest and some generics make 90 deg adapters that seem to be slimmer. While they may not be perfect they are likely better than a long small power cord. Reistance is additive. The longer a piece is the HIGHER the resistance. So this short piece, even if of mediocre quality, should add minimal resistance. It isn't like a water hose where a kink acts as an orifice.
If it were mine, and I really liked the amp, I might pull the female IEC out, replace it with a strain relief to pass the cord through, and hard wire my upgraded cord inside the amp.
Jerry