I have bought some rg11 from dx engineering. It seems like good stuff. I wouldn't be afraid to buy their other flavors of coax.
I have been buying 90% of my coax from JEFA Tech for the last several years. I've used a lot of their 213 for mobiles and lmr400 equivalent for base antennas. I recently bought a run of their lmr600. No issues with any of it and they have good prices.
If you will be disconnecting it a lot the solid center conductor may not last long depending on how much you move it. Keep in mind lmr400 ultra flex costs more and has a bit more loss.
If you use lmr400 I would use a short jumper in the shack made of 213 so you can disconnect without bending the solid core cowaxe.
You can use this to weigh out performance vs cost.
http://www.qsl.net/co8tw/Coax_Calculator.htm
Let's say you have a 1.2 swr on ch 20 at the antenna and your radio does 4 watts. With 125 feet of 213 you will deliver 2.946 watts to the antenna. With lmr400 it would be 3.23 watts. Lmr900 would be 3.691 watts.
There's nothing to be gained with expensive coax at 27mhz you just need to be sure it will handle the power you plan to put through it.
