Thanks for the replies - that's exactly what happened - I took a quarter turn out of the truss rod and raised the A and D slightly at the bridge. Only a small change needed to adjust the intonation and all seems well.
I was really surprised by the big difference in tension - now that I think about it, even though they're "heavier" gauge strings a lot of that's nylon, so less mass means lower tension to get the same pitch. Next time I'll check first; a learning experience.
I thought Nylon wound strings might be too mellow but I find them brighter than the semi-flats. I like it and they look spiffy