I have played 4 game months with this mod.
I researched the sniper as soon as I could. Even if I kept it in reserve at first, I was glad to have a few ones aboard on my first terror mission : 3 reapers in direct sight of the skyranger, with 3 more a few tiles away.
Both weapons are very dangerous in alien hands. The first time I saw a Plasma blaster, it's in an Alien base, a floater tried to shoot across a window at a very steep angle, and blew himself up. The second time, an other floater (I assume) missed one of my front men, the shot flew across half the map and exploded in a starting room, killing one of my men and wounding 2 others.
The plasma sniper unlocks the plasma (ship) beam, at first I thought it was "too good" because when once I can use the sniper beam, I don't feel the need to use any of the others plasma weapons. But after all, this acts as an alternative to the heavy plasma : In early game, I always try to research one heavy weapon even if I don't use it immediately. It's because I was first a TFTD player, and when the Lobster men first attack, if you don't have the big guns ready, you're screwed.