Topband: coax change?

[Gary Smith]

I am in need of new coax. I have a run of 350' to my transmitting 
antenna (Inv L) and my K9ay is 200' away from the shack. The coax to 
the L is RG-213 and the coax to the K9AY is 75 ohm TV coax.

I need to put up an antenna at a 2nd QTH which will need at least 
150' of coax. 

I have a lead on 500' of times microwave LMR-400 and LMR-500 at a 
fairly decent price and the RG-213 is the least expensive. So I was 
thinking about putting the LMR-400 or 500 at my home QTH for the 
Inverted L & the K9AY and moving the 213 over to the 2nd QTH.

The question I am asking here is if using a lower loss coax like the 
400 or 500 would allow a significant difference that I would notice 
with my K3? I will be using higher bands during the summer. Getting 
more 213 would be the cheapest answer and I don't want to waste money 
if the benefits would not be noticeable.

Thanks,

Gary
KA1J