True Monoblocks vs Switchable Stereo to Mono Amps

are there any sonic advantages and to what degree in an amp designed from the ground up as a Monoblock, for example the older Jeff Rowland Model 7, vs using 2 Jeff Rowland Model 1s which are stereo amps which are mono switchable. it seems if the sonic benefits are minimal, then the advantage of having 2 Stereo amps would be a plus in the event 1 amp went down.
In most cases when stereo amps are switched to mono, they will not drive low impedence loads. This is not always the case though. If you will notice most of the time a companies monoblocks are actually two of their stereo amps run in bridged configuration. Krells KSA-80/KMA-160's,is one example but, the amp was designed that way from the begining.
This is a great question and I have wondered this many times myself. There are many comments about the downfalls of bridging amps. Why? What is the difference between bridging and monoblocks?
I'm not an expert on this but one difference is when you bridge an amp you at least double the power output but do not double the power supply. If an amp has a large enough power supply, this is not a problem. Often amps will not drive low impedence loads when bridged.