Length of Mini DisplayPort to HDMI cable So, I just asked and had answered this question, Mini DisplayPort to HDMI cable vs. adapter - for MBP mid-2012, about the adapter vs. the cable. I am leaning toward cable now, but was wondering about the 3ft, 6ft, and 10ft versions. I'd likely go with 6ft. But my question is, will there be any degradation in performance due to the length of the cord(s)? In other words, will the 6 perform better than the 10 and the 3 perform better than the 6? 

Yes, I realize we're talking about a grand total of about $10 here, but it's less about that than it is about my desire to avoid having to re-replace something! Thank you!
Short answer:

Yes, the cable will be fine.

Long answer:

HDMI and Mini DisplayPort are digital signals, so either the signal works or it doesn't.

As cable runs get longer the signal is more prone to interference and signal loss that can result in no video, but unlike analog video such as composite video there is no loss in quality, just no video at all, or constant cutting out.

Given that you are really only looking at 10ft/3M this isn't very long at all, and as long as you buy from a reputable supplier the cable should state it is rated for 1080p at 60fps and if it was made 3 meters long it should work without question.

In my own experience signal issues with HDMI cables only tend to start to manifest at much longer cable runs over 10 meters / 30 ft, and at higher resolutions or frame rates which exceed what the cable was designed for, or when the cable is not from a reputable supplier.