I just took a first life rogue out of mothballs and got it to level 17...starting to question whether a 1 or 2 level splash in monk would make sense for an assassin.
Downsides of the splash are as follows:
1 level - lose the assassin capstone (+2 int +4 sa dice), lose a handful of skill points (though I'm int-based so that's no big loss) and 1 assassinate dc (2 total with the capstone loss)
2 levels - lose 1 rogue feat (either crippling strike or skill mastery), a few more skill points, 1 sa die, 1 more point of assassinate dc
1 level splash
1 more feat. Given that this was a Drow I'm looking at only 7 heroic feats. I'd love to take at least 1 actual epic feat in epic levels (Improved Sneak Attack) so that's 8 total heroic feats I can conceivably fit in. TWF, iTWF, gTWF, Precision, and Improved Critical (piercing to 20, slashing at 20) are must-haves for 5 locked in feats. Weapon Finesse is probably needed...I could get by with just daggers/kukri's but the moment I switch to something else I'm hurting. Since I'm going int-based with just enough dex for Improved Sneak Attack I'll want Insightful Reflexes as well. Unless I'm mistaken on Finesse that's 7 feats I'll need. I'd be spending a level 21+ feat for anything else I take...I think Dodge is pretty important...as a drow it nets me at least 6% (more depending on if I splash). I'd love to take Toughness or Sap as well but those are likely not happening - a 1 level monk splash would make Toughness or Sap possible. Since eMG don't uncenter a monk I'd be able to be in stance as well - that would be additional hp's and a bit of PRR (more on that in the 2 level splash section).
More importantly than the feat though is the enhancement trees. At level 1 Ninja Spy gives us 1 sa die (replacing one of the 4 we lost from capstone), 3% more dodge, and access to the faster sneaking enhancement. We'd actually be able to sneak at full movement speed. To me that's the most compelling part of the splash - full movement speed while sneaking. And level 1 Shintao opens up 10% extra off-hand attacks (as well as 10 positive energy/5% healing amp).
Finally, this gives a very viable option for DPS versus enemies that require bludgeoning damage - handwraps. The increased attack speed coupled with some good Fort bypass could yield good damage against skeletons for example. There are plenty of good wraps against the undead...it's harder to get a nice set of light maces.
2 level splash
Having 2 extra feats actually makes me want to go a bit different route. Rather than using the 2 feats to make things easier to fit in I'd make it harder to fit them in - use the Monk feats for Dodge + Finesse and then take Adept of Forms/Master of Forms as the two replacement feats. That would mean picking up Toughness at level 28 if at all but 2 levels of Monk opens up Shintao T2's 15 extra PRR in earth stance for a total of 27PRR.
Just wondering what everyone's thoughts are...hadn't even considered a monk splash but now that I'm about to hit level 18 I figured I better make up my mind now so I don't have to burn a good heart to fix anything.