AFAIK .. "AEG Snipers" are generally given a similar role, as a DMR. longer barreled AEG's that are generally a little more accurate than the average.
Still have to meet the general field limits, and if the player isn't playing it smart, can be at a disadvantage to the rest of the field.
Get a general purpose AEG and mix it up close and personal on the field for the first little while before moving on to any sniper platform.. you might find that being a marksman is way more boring, and at more of a disadvantage than you thought, as it applies to airsoft. It takes a lot of skill to be somewhat effective on the airsoft field, and it often involves a lot less action.
It really isn't a new player's role - and with the amount of new players that want to be sniper marksman, if they all actually got them, some games would be awful slow with a dozen noobs hiding in the weeds and no action going on, except the veterans cleaning up the weeds at the expense of the game's objectives, and watching the dozen noobs walking dejectedly back to respawn, to repeat the cycle.