whether I should keep/return the Insteon stuff I find myself wondering if UPB is a viable option I should be also be considering ?
		
		
	 
Yes, Martin at Automated Outlet is a big fan of UPB.  While I was at EHX I saw UPB first-hand, and I liked what I saw.  Switches seem very solid, and I like the look.  I'm now the proud owner of a Simply Automated UPB Starter Kit (thanks Martin!), so I hope I'll get to play with them soon.
My initial impressions from what I saw at the show:
 - not quite as 'quick' to turn on as Insteon
 - very solid feeling switches, but different brands have different feels - so try a couple out to see what you prefer (I personally didn't like the feel of HAI switches)
 - large - a bit larger than my Insteon switches, so maybe tough to get into crowded electrical boxes
 - no dimmer level indicator
 - switches are configurable - multiple toggles in one switch, half toggle/half scene controller, etc.. - pretty cool
People rave about UPB signal reliability, so it should be less sensitive to noise than Insteon.  One thing that I don't like is they don't seem to be moving towards RF at all, though there is an X10 bridge available.
If I had to choose between Z-Wave or UPB for lighting, I like the IDEA of Z-Wave, but for actual PRODUCTS I like UPB.