When I joined OSDE a few years ago, the only difference between 210 and 310 was in hospital affiliations. The best hospitals weren't on the 210 plan, but the list of practitioners, labs, etc. was the same. The price difference wasn't that great, so I elected 310 and was glad I did when my appendix ruptured a year later and I was rushed to Trinidad. Terrific hospital!
I've received no notification of any changes so far from OSDE, so I don't know if there are any changes in the works for the 310 plan.
Prices have increased in line with everything else. My original premium in 12-2007 was $578. The latest is $1,022, less some discounts for my payments as a monotributista, for a net of $861.89. (I'm in the Senior class, over 50.)