Not sure that a 160w Mega Ray would provide like for like the same heat as a 160w Arcadia.
The 160w Arcadias are IMO less intense in their heat - during winter you might even need additional heat. I think the MR 120w is more like the Arcadia 160w.
If you get a 160w MR my only worry would be that it could be too intense, especially now we are getting the milder temps outside - even if its on a stand there's only so far a stand will raise in height to lessen this heat.
Easier to add heat (if its needed) by getting the lesser intense Arcadia IMHO. I have had a 120w MR and I still have it as my spare. I also have an Arcadia that I'm using now and their warranty and service I have to say is superb.
I can't comment on the solar Glo bulbs but I trust what Al's test showed in that - they are not that great.
If you do get a combined, think about investing in a solar meter (if you got some money rattling around
) This is the only test kit that will give you the true UVB output of your bulb - new or after a period of use.
Good luck
xx