I went from the LP3 to the 5.3 and then added the outboard power supply when it became available. Though I never went back to do any comparisons, I feel secure in saying that while the smaller unit stacks up well in terms of neutrality and tonal balance, there's a significant gain in headroom as you go up the ladder, especially in the ability to handle high frequencies without any grain or distortion. If not for the fact that I listen to a fair amount of opera, lieder, etc., I probably could have been content with the LP3 over the long haul, but given my musical tastes, it was definitely worth it to upgrade.
