Climbing as a substitute for Flying, is a really good idea.
I like it.
The Healer Kit + feat + use object trick, is dirt cheap-est healing.
For the emergency purposes in-combat, you're effectively trading
a Bonus and most of your Move to give to a currently downed PC
most of a round, and defensive action attention.
And you have 3 or more rounds to figure out when to do it.
UMD keep getting better and better.
If your DM is not handing out Wishlist (and they shouldn't be)
the Very Rare and Legendary magic items are random enough,
the party should have 3 or 4 items otherwise unusable.
Thief gets to use them.
Thief is still in my "ultimate" party even with it's other quirks.
Further out, the Tome'lock's Tome is fair game,
anything the Wiz Artificer hands out,
probably all of the Wiz Techno thingy,
that 5 level prc thingy (wtf I forgot already).
There's gotta be more.
Weirdly, the Thief has an incentive to be in a party
with as many of those complimentary classes as possible,
but only up to level 13. Kill (or "kill") the party ho hum.
Go join a new party, where he slums around ultra-kiting
until that group has finished level 20. "Kill" that party.
Then go join yet another party to finish out his own advancement.
mostly T.O. nobody is playing like this