first and foremost --
disclaimer: I've no bias towards any one led manufacturer. we sell leds from most big manufacturers, including ecotech, pacificsun, ghl, ais and maxspects.
That being cleared, i think it is wrong to say one led is 'superior' than the other in "all ways". The r420r might be perfect for your needs, but might not necessarily be perfect for others.
You mention no reds and greens as a plus for maxspects -- i would have to disagree with you there. Not all reds and greens are shown to increase hair algae growth. There are two spectrums of reds in leds that i'm aware of, one of which does promote algae growth while the other does not. In-fact, i firmly believe that all colors are extremely essential for your corals to retain and bring out their colors. While the corals are supposed to be able to get the red spectrum from the warm white, having the additional reds and greens won't hurt at all. Plus, your fish would look much better when these different spectrums are in there. As a real life example, we have our ornate wrasses that look 'ok' under our blue and white lights. I tried on the cheap chinese led fixtures that i got, that contain red + green + uv lights, and the colors on the fish were absolutely unbelievable!
The increase in the amount of leds, how is that necessarily a good thing? (it's funny your brought this up, i had the exact same conversation with someone else recently) ok, you are getting more leds for your money, but if they're not required, then why have them? I'm not saying it's a bad thing, but i don't see it as "the reason to buy one over the other".
Built in controller -- yes, i agree. Ai's should have included the controller instead of skimping out. Not denying that at all.
Legs and hanging kit -- to me it's not a big deal, but i agree, ais should have included those especially when the unit costs so much.
Better appearance -- all i'll say is, beauty lies in the eyes of the beholder
everyone has their own taste.
One thing you didn't mention is the control. One of the biggest pros of the vega is the 20 channel control. Compare this to 2 channel control on the r420r. While it might or might not matter to most, i feel comparing the two leds, without bringing the best points of both is not a true comparison.
I would be more than happy to do detailed un-biased comparisons for anyone once things calm down a little bit on our end. Right now i plan on comparing growth and colors with pacificsun tritons, cheap chinese leds, and possibly ai vega. If pocket permits, i would more than gladly add maxspect r420r to the bunch.
And please don't take this post personally -- i'm just trying to add to a valuable conversation.