The reason 1/4" barrier line was recommended is due to the minimal amount of beer the line carries versus 3/8". The ideal set up for any draught system is one that the least amount of beer between the keg and the faucet. Plus, barrier is much more friendly to the beer than vinyl, which is antiquated technology.
If you are 100% certain that you can maintain temperature 24/7 from the keg to the faucet and you are happy with your existing system design, go for it.
Scott Zuhse, Instructor
Micro Matic Dispense Institute