There's lots of untested effects of Atma, and making a new thread for each one seems silly. So hopefully we can get some good testing and discussion on atmas in here.
To start off, I ran a fairly simple test this morning while skilling up in Abyssea. I used VV + GH and parsed myself on crabs. I used MNK/NIN /w Earth Staff and no DA+ gear.
57 Double Attacks in 988 melee rounds, according to Kparser. This puts VV at ~5.77% Double Attack rate. A few people had commented that they were getting around 5% DA rate, so this isn't a huge surprise.
485 crits in 1045 total hits = 46.41% crit rate. The obvious problem is that I don't know my dDEX against crabs, but assuming it was capped, this would mean 5% base + 15% dDEX + 4% merits + xx% GH = 46.41%. This makes GH about ~22.4% crit rate at the very least, more if my dDEX wasn't capped. I don't know the statistics that well, but it seems that over 1,000+ hits having my crit rate vary by more than 2.5% seems unlikely. Does this mean that GH is probably closer to 25% /w capped dDEX? (And if so, that would imply some kind of crit cap when RR + GH are used together.) In any case more testing is def needed there~
And last~ Tested the counter rate of GH. Was hit 120 times, countered 236 times. 236 counters / 356 total hits = ~66.3% counter rate. My melee accuracy was 95%, which leads to a 69.8% counter rate. AF2 Feet were used during Counterstance which was on nearli full time, and Usu Hands were used full time. I'm guessing that leaves me at 62% Counter Rate + xx% from GH, which would be about ~8%. Unfortunately small sample size is small, but the counter+ seems to be between 5-10%.