If you compare Ushio 10ks mogule and DE running off the same ballast (M80) here is how it looks:

Mogule, not shielded has PPFD (similar to PAR) 159
DE, not shielded PPFD 104
DE shielded (you can't run these not shielded) PPFD 84

If you run the mogule 250W ushio with a standard M58 ballast it drops to 118.

Mogule bulbs do produce more PAR for the same wattage; in this case almost double. I was surprised to learn this back when I was shopping for lights. The HQI ballast, which most people use with DE bulbs, is probably the reason DEs have such a reputation for higher output. The color temps tend to be a little higher for given bulbs with DE; with the ushios its somehwere around 8900 for the mogules and 10000 for the DEs. Another reason DEs got their rep, I think, is because they're usually in better reflectors, but the lumenarcs changed that. If you're looking for the highest PAR out of a particular wattage, you want to run mogule bulbs in lumenarcs, without a shield.

On my small tank, I'm using a DE pendant, because I knew I would not be able to use actinics and I wanted the color/PAR combinaton of the phoenix 14k. I also think that a mini pendant on an open top tank is probably the easiest way to avoid heat problems in a small tank.