((The way I see it, the Shard Rifle is worse than a laser or a gauss rifle for HMRC purposes, but it's better as a standard issue army weapon.
The gauss cannon has the overcharge shot and the ability to use specialized ammunition which give it the ability to be much more powerful and much more versatile. It can also work underwater, although I don't think that's very important.
The laser rifle has no kickback (and thus doesn't require the user to spend any points in STR, which is good for newbies) and has the ability to make shotgun blasts, slice things, melt things, disarm people and make sweeping attacks thus creating a line of death. It is therefore much more versatile.
The shard rifle fires shards that are less powerful then gauss shells (although they are more powerful than a laser). You can't do a sweep to hit multiple targets like the laser rifle (although you could probably hit two or three targets at the same time with full auto). You need concentrated fire to damage anything armoured like with the laser rifle, only with the shard rifle it's harder, because it has some kickback. And it is not at all versatile. It doesn't even have a variable power setting. Even so, it is much more expensive and requires an external generator which can easily fail and require repairs in case of damage to the weapon or the user.
If a newbie was faced with the question of where to spend their money, in my opinion, they would probably not choose the shard rifle if they knew what they were doing, unless they were faced with an imminent battle against the UWM or another mission that is likely to involve extended combat. They'd be much better off spending the money to buy a crystalline projector so that they could get an almost guaranteed kill with every hit plus a melee weapon (which is what matters most, since battles in ER tend to be rather short). Or spending the money to buy a laser or gauss rifle so that they have some left over to buy more and better stuff later or to buy other useful equipment like scouteyes or medkits.
And neither would a veteran. They'd be much better off spending 7 tokens instead of 5 to buy the Sibilus, which is vastly superior in everything but ammo capacity and ammo cost.
The only balancing thing it needs in my opinion is a strength requirement (3 or lower, probably) with a greater one for automatic firing (around 5, probably), since it'll have some kickback, plus you have to carry a heavy backpack.
On the other hand, for missions that include prolonged combat or for an army that uses standardized equipment, where having cheap yet powerful equipment matters, where there is time for repairs and medical attention, where prolonged suppressing fire is necessary, the shard rifle would probably be better, although there should still be plenty of gauss and laser rifles to go along with them.
EDIT: Just realized this isn't the OOC thread.))