does power cord length matter? fact or myth?

Absolutely - HUDGE difference.

Cutting it will (at best) provide half the performance O.M.G.

Who would do this - O.M.G.

Short answer - if you'll drink the whole power cord kool-aid, then, no doubt you'll buy into this one.

To put bull aside, it will depend on brand, your equipment, on degree of resolution your system is capable of, current quality and your hearing.
To put it another way, there will be a difference, and you may or may not hear it.
Some manufacturers and audiophiles recommend power cords be no less than 5' long. I remember that someone on this forum said that it is true for Noth American 120/60 current but is the opposite for Euro 220/50 current.
Personally I only have 5' cords and don't think about it.

Shunyata does not recommend power cords shorter than 1 meter. If you do a Yahoo search you will find their brief explanation.

I think this is a mapleshade.com thang

I seem to recall something regarding minimum lengths for ICs and PCs in their catalog. But I don't recall the rationale (if there was one).

Mapleshade actually says 8 feet is optimum, not minimum for speaker cables.