From what I've seen of him, Alex Foster looks a decent player, but another in that mould that we've seen before. Probably not quite big enough to be a really impactful second rower and not quite quick and skillful enough to be a centre.
That being said, he's a better option than Blythe. who currently fills a similar role. Probably a decent squad player and maybe a good bench option, but I'm not convinced he's good enough to be a starter week in, week out.
Iliess Macani, I don't understand. Reminds me a lot of Will Sharp and will probably end up in a similar position. Bouncing around Championship teams, scoring some tries because of his pace, but never really setting the world alight. I don't think he improves on Moss, Clare, Caro or Ryan though.
Macani & Ioane I can't say I've seen enough of to really form an opinion.
I worry a little that Rohan's former London links are swaying his thinking. Although it could equally be that those links let him know there's a couple of gems there that have yet to be properly discovered.