This dude looks incredibly powerful. Considerably more potent than any other 8-stone models I know of.
Taking damage to add any suit you like is a good trade off, but when combined with Luck Thief and Winston's high defensive stats, it's likely that he's going to be gaining that health back at a reasonable rate.
Fortune's Favor would be potent if it just let you look at, discard and replace the top 4 cards as you choose for 1AP and no target number. But add the option for free movement on top of that...
Basically, my 2 scrip is that Winston doesn't seem to have any down-sides to him and would probably be an auto-include in any Explorer's Society crew, even OOK.
I like the fluff and the character design is awesome, but currently Winston Finnigan feels unbalanced compared to everything else in 3rd Ed.