actually Heinz, what you said is technically incorrect. i don't want this starting off with any controversy, but i do need to make sure everyone involved, or is following this, understands why the AP902 is the exact skimmer to match against the BK250.
although there are several other factors involved with determining how effecively a skimmer will function, including neck width, square area, pump height and chamber dimensions, all in particular proportion to each other, the most significant one when comparing any skimmer to another, all other things being equal and solely on technical specs, is air draw.
according to the Royal Exclusiv website, the BK250 draws 1500 liters of air per hour. comparitively, the Deltec AP850 draws only 900 L/H. the AP902 draws 1600 L/H, and while it is slightly higher, the difference is not significant, especially when compared to the 600 L/H difference with the AP850. the number of pumps really doesn't matter in this either aside from BK being able to claim that their one pump is better than 2 of the Deltec's, if this is really indeed the case. however, even with Deltec having 1 extra pump, the cost difference (based on today's exchange rate of 1.31) is relatively similar, the Deltec being $1735 not including shipping from within the US, whereas the BK is $1780 without shipping from Germany.
i hope this clears up any potential misconceptions of skimmer dynamics, at least in regards to this scenario.
beside, as you said, the BK250 will smoke the 902 anyway, so you have nothing to worry about right?
right??
Doug