imo opinion there is no reason you cant get a 'decent' yield with fluoros and cfls. will a good gardener get more from hps than cfls? maybe, depends on the gardener, though usually the answer is yes.
if you browse the forums, some great gardeners have done some great cfls and gotten comprable yields. you just need to make sure the lumens are there. if you have a SHIT TON of lights, and the proper spectrums, you could potentially do something great. iam using a 4ft 6tube T5 fixture that puts out about 25k lumens total. during flowering, ill be haning 4-5 150W (not 150W equivs) cfls for additional lumens/red spectrum/light penetration. as far as i can tell, i should be able to get 2 or maybe even 3 plants to yield well under these conditions (about 40sq ft, lightproofed).