As for the WPG on small tanks - it just doesn't work.
I have a 1/2 gallon with a measily 7w over it - if I were to go with WPG, that would be 14WPG...
30w over 10g is a pretty decent amount, but not necissarily HIGH lighting in respect to the "WPG rule". 55w PC plus 20w NO over my 20g long isn't even "high", IMHO.
I'm going to do a 15g-high(sameW & L of a 10g) lower-light and will go with either two GE 9325k 15w bulbs, or one of those and a 15w 6700k bulb for a total of 30w.