What are the advantages, and what tactics did you use?

I surround the area I least want them to come out of with enough firepower to dissuade them from that point.

They won't be sending an ISD or MC80 so it is a ship that can be killed with some effort

I've had a few recent games against some friends. They both play rebel. They both picked the Salvation across 4 total games. I won every game.

Leaving a Gladiator (especially Demolisher) near their expected point of arrival gives you a great ability to respond to them. You are typically maneuverable enough to get out of their favored arc, and if you are using the Demolisher you are probably landing a very solid shot, too.

Alternatively, I've had opponents select it in tournaments, where I nearly always won (I should've won all of them, but there were misplays on my part.)

And sometimes it's the best of a series of bad options.

I pick it quite a bit, its not hard to force the enemy into picking a point that they do not prefer.

My opponent had Yavaris and B-wings. I chose Hyperspace because the others didn't seem like good options. I setup near one of the points, and I timed it so that when my VSDs would be past the hyperspace point, Demolisher would come in.

That was the turn he chose to exit hyperspace. His options were quite reduced, either wait another round and be too far away with the B's, or exit hyperspace far away. He setup so I wouldn't have a double arc. Two good shots with my demolisher (side and back after moving) and he was on 1HP. Sure, he got to fire, but only once. The closest VSD also had enough speed to escape the B's, so that's almost all the damage they could do all game. Unfortunately I couldn't activate my VSD instead of Demolisher, because I would have entered the firing range of the rest of his fleet.

I chose it in a Sullust match because the alternatives were worse. He had two Assault Frigates and two CR90s; I had three VSD IIs with Motti. He set aside an AS and deployed left-center. I set up far right and slow rolled (innermost VSD started with three nav commands so I could drop to speed 0, save a token and then jump to speed 2 when necessary. Middle SD was speed 1; outermost was speed 2. This let me pivot my line to face him while maximizing the time it took until shooting started. My opponent was forced to either commit piecemeal or delay hyperspace exit. He chose the latter, which was fine by me because fewer turns of shooting favored my more durable ships. In the end only the two CR90s died, one by flying off the edge.

I chose it at Sullust against a Vic/GSD build with loads of TIES. I had 2xAF and Salvation build.

Just stayed away from his VIC and then just waited until he hyperspaced his Demolisher GSD in on turn 4. Hammered it and 4 squadrons of TIES for a few shield damage. VIC played no part. Not overly afraid of it.