They work but not to the extent of actually seeing any muscle growth (maybe on the long run). They increase IGF-1 expression and HGH stimulation by signaling the pituary to release hormones, so they're secratagogues.
However, using secretatogues you are limited to the quantity of hormones present in your glands wich mean you cannot get over natural production using secretagogue ever. You can only increase the frequency of pulses by using them many times a day, creating spikes in hormones. Using CJC-1295 or mod grf-1-29 makes you produce more HGH, leading to an increase in the release of hormones when there is a pulse. Combining the two products seems logicial since you basically get your glands to produce more hormones, then signal them to release it in the bloodstream.
There are no studies done when combining the two drugs together...yet. Funding for those types of drugs is hard. That's why even Ibutamoren who is not only as efficient as injectable peptides but orally available, is basically shelved at that point. There just isn't money in them and it is very difficult to meet endpoints in research for those substances (how can you fund a study showing kids with growth issues grew using your product? At best, you can say "It helped release hgh" but you won't ever find the fundings to do a study long enough to show a real increase in growth...).
I would use GHRP-2 instead of 6 if you are worry about eating too much as it causes a scientifically proven spike in apetite in healthy subjects. Also, using CJC-1295 instead of grf-1-29 causes a continuous release of GH instead of shortened production. There are many opinion on the subject but increasing production for days would cause GH bleed but in my opinion, it is a rather healthy elevation of serum IGF-1 and HGH over longer period of time that can be resorbed when switching the drug. Abnormal growth in bones is only seen in people using aburd levels of HGH over long period of time. In healthy volunteers, gh production was increase several folds by using CJC-1295 wich mean you could have supraphysiological concentration of HGH in your blood by using it. I don't think a GH bleed is something to worry about for abnormal bone growth as long as you cycle your use. Besides, the purity of those peptides is questionable, even from reputable resellers (something I learned the hard way) so cycling is rational. But since it is getbig, don't be a pussy and stack it with your 3 g's of Test a week :-).
Personally, I've switch to Ibutamoren because it is available orally and has the same benefits as CJC-1295 and I do see quicker recovery, healing of tendons and joints, increase in skin condition and energy levels. The effect when using injectables was more noticeable: I was swollen and had major water retention but I don't like pinning (except pharma grade stuff :-)
Here are some articles:
http://press.endocrine.org/doi/abs/10.1210/jc.2005-1536http://press.endocrine.org/doi/abs/10.1210/jcem.76.4.8473389http://press.endocrine.org/doi/abs/10.1210/jc.2006-1702http://onlinelibrary.wiley.com/doi/10.1067/mcp.2001.116514/abstractTLDR: they work not to the extent of real HGH at least not in the doses needed for bodybuilding (many times over what is naturally produced).