You could put R2-D6 on a Gray Squadron and give it Marksmanship, that would give the A4/Ion some bite for both shots.
Is that worth 29 points?
Maybe. I just ran some numbers, a Y-wing with a-4/Ion and Marksmanship would do more average damage (!) than two Tie Fighters at range 2. Add to that the possibility of crits on the first shot, the control aspect of Ion, extra PS vs 2 Obsidian coming in at 26 points. The cons would be maneuverability and extra cost, less damage at range 1, less damage at range 3.
So yeah, maybe is my final answer. We shall see.
Don't compare it to the opposition - compare it to what else you could take in your own squad. Consider the opportunity cost.
29 points is Wedge. It's Farlander, or a Blue Squadron with HLC, or one point shy of a pair of A-wings, any of which are tougher, more maneuverable, and hit just as hard, if not harder. It's two points shy of a full focus factory Kyle with an ion turret of his own that's handing out focus to the rest of the squad, although admittedly more fragile for it.
That's what you need to compare it to, and I don't think it looks terribly appealing in the comparisons.
Have I mentioned you can shoot two different targets?
I don't care about cost of opportunity, because it means I would compare apples and oranges. This is neither a damage dealer, nor a pure Ion dispenser, but a bit of both. I withhold my judgment until I've seen it on the table. It's interesting to see how damage + Ion on a single ship plays (have you tried 4y Ion? it's a 3-hour game, nobody can hit you but you do almost no damage), another question is whether you can keep a target in your sights with the Y-wing (now that you're really trying), whether you can finish off a ship while Ion'ing another... There are open questions that will get answered in testing, not in this phase.
So it's still a maybe