Chris at premier can cover the question about MOA at what power at what range. I had thought 5/8 MOA was 5/8 MOA, but I have been corrected in the past so I will not present that info again...LOL.
I have 3 of these scopes and as mentioned they are the "Air Rifle" EFR marked versions that will focus a little less than 10M. I shoot 10M in my basement and I can focus to read the fine print on the pages at that distance.
RE:"Any disadvantages of getting it reparallaxed so near?"
None, turn the AO back to another setting to shoot Small Bore, High Power, or any other distance from 10M to infinty.
Call and talk to Chris, he is a good guy and they stand behind their work. He can put what ever size dot you want in it at the begining w/o a price change as I understand it.
Only negative I have ever had with these scopes is that from time to time I have wanted to slap one on my hunting rifle, 6.5-20 would be perfect, 18-40....Different story, LOL.
WARNING!!!
You will probally start a "war" here with power settings and etc. There have been many talking about not "outshooting" powers below 20 and etc. I'm not that good (guess I'm suppporting their arguement, HA-ha) BUT I do watch my hits and misses through my scope during follow through. I love to see a pig hit high in the hump to go spinning back or the Ram to go straight back when the shot is right. To me the dot on 40X is about 3/8 MOA at 100 meters, only thing I base that on is a target w/ use with a .5" center circle, I can still see the circle w/ my dot inside it, just a bit of it... Dot is perfect for shooting at 40X, Way too big for shooting at 18X IMHO. Example is pigs, I can tell when I'm "on" the pig, I just can't tell you what part of him I'm on at 18x . On 40X, you can put the dot on his ear if you want... All in personal prefrence I guess. I have no problem being on call shooting at 40X, my spotters just can't figgure out why I pull the trigger while I'm off the animal, LOL!
Chicken