The benefits are purging the receiving keg and closed xfers, which is definitely better. Every yeast reacts different to pressure, some ale yeasts produce esters under pressure no matter what. Until I learn how an ale yeast performs under pressure on my gear, I let pressure build natively to 3-5 psi and raise the pressure in the second half of the ferment and xfer fully carbonated beer into the keg. In split batches with a new ale yeast, I typically let the one batch build to 10 psi, for most ale yeasts there is virtually no difference in the glass. I don't think there are any drawbacks.