I think one of the problems you may have run into is not that the
lights are insufficient, but rather that they weren't lighting your
tank evenly. Even in my 20g long there is a slightly less bright spot
in the middle of the tank and at the corners - for the most part this
doesn't matter since I keep an amazon tank with mostly dim-light plants
in it anyway. But if you had the same setup as I do in a 30g long
aquarium you probably had some spots that were significantly dimmer
than directly under the bulbs. You might have done better to get
double sided sockets and put four screw in bulbs into the hood rather
than just two to get a more even light - but at that point it may be
better to just go with the standard tubes - which I suppose is the
conclusion you already came to.

I still think the screw in flourescents have their place though. Are
they "just as good" as a $100 hood with a high output bulb? Heck no.
But they can be the difference between "I can't afford good lighting so
I can't have real plants" and "Hey! My aquarium looks great!" I know
mine does, and I recommend the modification I made to anyone with
limited funds and the desire to recreate a more natural environment. My
tank now happily supports two Anubias barteri (well three actually -
one is in the process of splitting), three bunches of Java fern, one
Ruffle sword, two Red swords, and a nicely spreading patch of Water
clover (which I absolutely love).

I'd say that's worth a $30 mod that took less than an hour to do.

-Daniel