I have actually seen this set up for long cable runs to subs at some audio shops around the country. The F to RCA connectors I have seen have ranged from Canare to Radio Shack.

Most of the regular guys at these shops, the ones that are NOT the sales geeks, all say the 75 Ohm cable with the F to RCA connections are fine and no issues have arised.

I just switched out my old Monster brand sub cable for a 25ft 75 Ohm cable with F to RCA connectors from RS so I could test various locations for the sub. The sub response in its original location with the new cable was no different to my ears. All the connectors are gold plated and tightened down pretty darn good and the RCA connection is extremly solid. Is there a reason why this chould not suffice as a long term solution?