http://www.cheapassgamer.com/topic/281768-complete-list-of-pspminispsone-games-playable-on-vita/
Well it looks like the thread turned into a mess, and this is compounded by the fact that a bunch of games were removed from PSN. But it seems the Syphon Filter games were among the victims:
Syphon Filter: Logan’s Shadow (Only appears on the Killzone Liberation Syphon Bundle)
So I guess I can offer no advice, but what I would do is simply not buy the games. (why buy something which Sony does not intend you to, and which requires a PS3)
On the other hand if the games come in double packs, then that acts as a safety net, since even if the Syphon filter game doesn't work, the other game will probably work so it wasn't a total waste of money.
Or you could go to cheapassgamer forums and bug people for answers..
-- user InfinityCartier wrote on page 17 regarding Logan's Shadow "Yes. [it is better with Vita contros] it'll need some tweaking but the game has a lot of options "
-- user kstegall on page 7 wrote that he got Logan's Shadow to work by buying the double pack from gamestop.com
You could always PM them. But chances are if the game once worked on Vita it is unprobable that Sony would make it not work later... but you never know.
user Bullwinkle on page 5 wrote that he waiting for Dark Mirror to work in the US. But it was written in March 2012.