How are the effects and methods different? It was my understanding that mk-677 is also a ghrelin mimetic, only more orally available than ghrp6 or 2. I believe mk-677 increases the amplitude of GH spikes in a similar manner as the ghrp's do. So you are saying that mk-677 provides faster and different effects? I'm almost 40, and am looking for the typical things that come with an increase in GH...better sleep, improved recovery/wound healing, anti aging affects, recomp, etc. I'd rather not inject and just wonder why so many people inject ghrp 6/2 multiple times a day, when they could just take 25 mg mk677 orally once a day...im thinking that there must be some benefit?
Differences first:
MK-677 is not a peptide, GHRP's are (easy one, eh?)
MK-677 is oral, GHRP's are not (well, sure they are but not bio-available in this method)
GHRPS have varying affects on ACTH, prolactin, cortisol and GH. MK-667 seems to have less, to no effect here, except GH.
Dosing for GHRPs is in the mcg range, MK-677 is quite large at 25mg, most likely due to some digestion prior to absorption (I really don't know how it reacts in the gut, I haven't seen anything yet on this.)
MK-677 is interesting because of the GH stimulating similar to grhelin mimetics, since it's not a peptide. Most GHRPs themselves are worked over versions of ghrelin (which is why MT-2 does a number on your gut if you've ever used it) so all the sides are similar
Similarities
For effects, you listed them above except for the effect on other hormones. Basically MK-677 sounds like Ipamorelin in oral form, GH targeted. As for pinning or drinking, you got to remember the target audience for the products, as well as where you are reading about them (specifically here.) Most these people aren't afraid of needles, and haven't been for a long, long time.

The idea of anti-aging is about 20 years old, so the market is still growing for this term.
Source study (old, looking for something newer) I pulled from:
MK-677, an Orally Active Growth Hormone Secretagogue, Reverses Diet-Induced Catabolism
Hope this helps,
JK