When I first saw SW: Legions, I was really excited – extra star wars miniatures to use for Imperial Assault! But it turns out the models are a slightly different scale, which is really disappointing. My first reaction was "oh well, its a different game that I won't get. No harm, no foul". Then, I got thinking that actually it wasn't all bad.
I'm not particularly interested in Legion as a game, so I don't personally care about using IA models in that game (that's a whole different discussion). I also play exclusively campaign games, no skirmish. There was never going to be official Legion unit rules for IA, so if we were ever going to use those models they would probably need unofficial house rules, or be used as proxies anyway.
Here's the upside though, the models are about 5mm taller so look silly next to IA models. At least that's the human characters – luke, rebels and stormtroopers. We already have tons of those in IA, I don't need more stormtroopers. Sure, higher detail ones would be nice as a replacement, or to use as elite stormtroopers but it's not the end of the world.
What we don't have is a lot of vehicles. I generally use other manufacturers and toy kits of star wars stuff that's generally in scale. Having stuff like skiffs and speeders would be great even if only as terrain. Then there's the droids and aliens. Wookies will be huge, great for a large berserker unit. Combat droids can be any scale, I always assumed probe droids were bigger than in IA anyway. More creatures like the Nexu would be cool too, and again the difference in scale is not going to matter. Ultimately I think the only figures that won't be compatible for use in IA are the ones we already have already.
Now, if you want to play Legion with IA models, that's unfortunate and I would suggest just not getting Legion. As a wargamer, it doesn't look especially amazing, just a fairly standard, basic version of a tabletop wargame with cool models. Get it as you would any other game rather than one to use IA models with.
Edited by RED NED