With respect to the increase of the PAR, I believe it is due to a few of reasons:
1. Increased number of tubes.
2. The curve on the Sunpower reflectors isnt as sharpe as the curve on the PM reflectors, hence the more acute angle of curve on the PM reflectors would focus the light a bit more...I saw an image of the light spread from both fixture's reflector compared by a hobbyist on a Chinese website and the reflectors on the PM focus's light more than the slightly flatter angled curve on the Sunpower reflectors.
3. Improved cooling: with the extra fans on the PM perhaps the tubes are being cooled very close to 35'C and thereby producing max PAR?
4. Perhaps there are better ballasts being used on the PM? This is purely a guess though.
With regards to the swap of frags. I would love to get a frag of the Setosa...let me know in advance of you coming down to London, if I obtain a frag of the Setosa before you come down, then you can bring something else that takes my fancy. Will defintely give you frags of the Red Planet and Blue Tort. -I see sharing of nice SPS corals as insurance.
I gave a frag of my Red Planet to Paul at ACC and it is growing very nicely in his tank.