Been buying from Erik (Rkep) since 2012.
I'm quite fussy when it comes to grips and whenever I go abroad Asia or Europe I would try find a badminton shop and try some over grips.
I've yet to find a grip that suits my needs for the price of these grips. For me its always AC102 and RKEP G11 as my benchmarks.
I normally have cold dry hands so tackiness is ideal for me (and of course longevity). I prefer firm grip so I can feel the shuttle better.
# On a G4 handle, I would fold wrap G11 as base (on wood shaft) and another G11 normal wrap on top (I'm a size 9 glove, so this is pretty thin)
# I change top layer when I see some dull rips/imperfections which is normally about 1.5-2 months (if 2-3 sessions per week, 2 rackets), or when its time to restring my racket and I don't have time I put a new grip which gives better feel and "more power" to the strings, imo...
# Material consistency of these changes over the years but I tend to buy bulk (ie 60-70 pcs a go), so I can have time get used to the material.
# I find generally most colours are consistent except for the shades, ie black, white and greys (maybe placebo?), the odd pinks/red are sometimes different, I understand in some material plastics yellows and reds are "more difficult" to manufacture/perfect. Whether this plays a part, I have no 1st hand experience....