ataman's hi-pressure cylinders

Personally I consider where it is built and to what the country standards they have to test. As an overall consideration I would feel marginally better to select a higher pressure cylinder and only fill it to say 80%. Being that it is a Russian made gun, that does not mean the tank is or not made in Russia and that depends on your experience with Russian technology. I personally have found that they are just like anyone else, they have their well engineered designs and some that are a little closer to the margins of acceptable. I know this does not help that much but I would tend to fall to the side of it is a pretty well made gun and that the design has been tested. Due diligence on your part might be in order to prove out the quality.
As far as the pressure being a consideration in my purchase? Absolutely. Higher working pressures mean less fills from my tanks, more time to refill to higher pressures on the compressor. More wear and tear on the compressors, as they work the hardest at the top of their rated ranges. So yes, I prefer lower fill pressures. Like on my Vulcan it can be filled to 250bar, but I only fill it to around 220bar. Still plenty of shots with an extra margin of safety and less wear and tear all round.

It won't make a difference. 

If they're specified and used properly then they are safe. If they are not, then there is enough pressure to kill you with both 3000 and 4500 psi cylinders. 

really this shouldn't be a factor the tubes are rated for a max fill and even then the cylinder itself probly rated for much higher now the way I look at it the tube is fine is the valve is what would concern me being held under that kind of psi means the weight for firing it should be pretty hefty and my first thought is how long till the valve stem goes bad
also with ataman the thing that's made m scratch my head is the shot count with high psi fill and they say the gun is regulated now I'm no exspert but shouldn't a regulator increase shot count while maintaining consistance
http://www.pyramydair.com/s/m/Ataman_AP16_Regulated_Standard_Air_Pistol/4127Max Shots per Fill20Body TypePistolFixed/adj. powerFixedWeight2.2 lbsGrip SizeMediumCylinder Size108 ccShroudedYes​yet only suppose to give you 20 shots now I get that its at 18 fpe but really to me
​id rather take a prod for 350 and customize the hell out of it with the extra 500$
​and its cylinder is only 65 cc and the it can be regulated now
​mind you I am comparing this it the long version of the atman pistol I'm just seem to be missing the it better part for he cost

I would like to find out what the volume email is what the material is and what the wall thickness is. Short of thick heavy walls or titanium the volume must be reduced.

Why would you fill it to max anyways? Besides, a lot of tubes are tested for 600 bar, but that does not mean the reg/valve can Take that pressure. The max pressure is just "don't go above because it is not healthy"

My recommendation is don't fill above 220 bar and your gun will live a Long and Happy life without having to replace o-rings