mjgodden, I would switch to flying with SQ for your trips to Europe/US, but putting miles into A3. With *G, you're almost always guaranteed an exit row seat, at least I've scored 9/10.

And Exit Row in Y is definitely at least as good as Premium Economy space-wise.

I assume you don't buy the cheapest fares, so you should be able to get 100% when flying SQ on S, Y, B, E, M, H, W, U, L, K when crediting to A3.

This will grant you lounge access everywhere, a good (very good) chance for exit row seats on SQ as much I know, quite good redemption rates with A3, and still the opportunity to switch to TG or any other *A should SQ try some weird changes once more..