Stout HLT Herms coil size

[Brewsader1]

For anyone that has a stout HLT with a herms coil, I’ve seen a few comments about the 3/8” diameter coil being restrictive. I’m looking at a HLT with a herms coil that size...is it really a deal breaker?

It’s a 20 gallon HLT and mashes could go up to 15 gallons. If you have one and put on a 1/2” or bigger upgrade, how much of a difference are we talking?

Thanks!