Thief / assassin / acrobat mashup

I found myself, some days ago, browsing the AD&D 1st edition Unearthed Arcana, and re-read the description of the thief-acrobat split class for the first time in quite a while. It got me to wondering whether that class' abilities could be integrated into the standard thief class, without requiring a separate sub-class. In class-based games this is how my tastes go - I want a few very archetypal classes (fighter / thief / magic-user), perhaps with a sprinkling of options within each one to give a bit of variety. The number of classes in AD&D 1e/2e is too great for my sensibilities, let alone the madness of all the classes and 'prestige classes' (or whatever) in 3rd and 4th edition D&D.

The thief-acrobat abilities seem like the perfect example of the kind of 'options' I'm talking about for a class. You're still a thief, but you can choose (at character creation, ideally) if you want to specialise more in traditional thievery or in fancy acrobatic tricks. Likewise, I think the skills of the AD&D / Advanced Labyrinth Lord assassin class could easily and pleasantly be integrated as options for the standard thief. That's another class which, according to my criteria, isn't really necessary - it's just a thief with a couple of skills swapped out.

So I compiled a list of all these thief-like skills, including those from the acrobat and assassin:

1. Pick locks
2. Find & remove traps
3. Pick pockets
4. Move silently
5. Climb walls
6. Hide in shadows
7. Hear noise
8. Back stab
9. Script: Read languages / Use scrolls
10. Disguise (as assassin)
11. Poisons (as assassin)
12. Tumbling (as acrobat)
13. Balance (as acrobat)
14. Jumping (as acrobat)

So, just in theory, a newly created thief character could simply pick 9 out of those 14 skills.

(Note that I've not included the assassin's 'percentage chance to kill things automatically' ability - I've always regarded that as a bit over-powered and silly. Besides, it's sort of just a variant on back-stabbing for multiplied damage.)

The script skill, which includes read languages (usually gained at 4th level) and use scrolls (usually gained at 10th level), could probably do with a bit of expansion. Ideally all of these skills would provide some benefit at 1st level. So I'd extend the read languages ability (at a lower percentage of success) to 1st level, and possibly include some kind of code-breaking abilities too, which would be pretty useful for a thief.

Likewise, I'd consider giving back stab a progression of sorts (as it does in AD&D, but doesn't have in LL), so the damage multiplier increases at higher levels.

Also the poisons skill would need some kind of progression - perhaps a percentage chance to analyse or even create poisons?

It'll need a bit of work, but I think it's a pretty promising idea...