I've made plenty of experiments with goal to find best light type for keeping mothers and young plants in vegetative state.
CFL's I've tried were available in two outputs: 115W and 180W and two colors (three including combination of both) of spiral spectrum: 2100°K (flower) and 6500°K (grow).
I've used both power outputs and also experimented with flowering under 2700°K
More powerfull type:
Establishing new mother plants under CFL:
When using for grow phase, I've noticed that plants are more vigorous and branch really well. I believe that production of clones can be slightly increased with CFL. The problem I suspected is that light doesn't reach into distance. I confirmed this suspicion by measuring lumens with light meter. So I'd say using CFL for large mothers is very impractical. And mother plants can grow pretty tall if you keep them for years :).
So I'd recommend to use CFL for vegging young plants before they grow to tall or before switching them to 12/12.
One thing really surprised me and that was short operating life of these lamps.. It starts with if you are lucky enough that DHL delivers the lamp in OK condition... There is about 50:50 chance that the lamp won't make it to you together.. It is extremely fragile, so you have to be very careful when inspecting the light, moving it and handling it around your grow room. And if you don't break it yourself, rest assured that it will stop lighting very soon... I've got about 20 of these and 5 of them made it to second year (they were not lighting 24/7). Practically every month one of them ceased working...
Summary: Usability for Vegetative Phase
For vegetative state my opinion is that CFL when compared to MH (metal halide) offer slightly better branching, but light distance is very limited.