a good 600watt hps gives off over 90,000 lumens. on a good day a cfl will give off 70 lumens per watt, so 25x70 = 1750. you've got two of these so that's 3500 lumens. that's less than 4% of what that single 600 watt hps puts out.
the good side to cfl is that you can have it pretty much touching the plant without burning it. i say get some dividers for the sockets, you can get em at home depot. it's a little Y shaped plastic adapter that you screw in to where you would normally screw the bulb, but instead of a light emitting bulb, it's two more sockets. so you're turning that one socket into two. that way you can screw 2 cfls into one socket. i would even take it a step further(i've done this without problems). let's say you screw 2 of these Y shaped socket adapters into the 2 sockets you have, then you would have 4 sockets for bulbs. but instead of that, on each of those ends put another Y adapter. so then you would have 8 bulbs running on 2 static sockets.
you were saying money is a problem. those Y adapters at home depot are about $2-3 dollars each, get some.
8 cfl bulbs at 70 lumens per watt make 14,000 lumens! that's bumping up to 15% of that 600w hps bulb. that's a jump of almost 11,000 lumens for a couple bucks and a couple more bulbs! not to mention how close you can put them without hurting your ladies.
it's not hard to conclude that the more light, the more potential for growth. your competition and idol is the sun, which on a sunny day shows off 100,000 lux.(lux is lumens per square meter)
PS- make sure you get CFLs with a high Kalvin rating like 7000(blue spectrum light) for early stages and vegging, and some 2000K or 3500K for flowering(red spectrum light).
class dismissed