So this post was just to show an example of a potentially fairly strong multiclass build that should work really well after the enhancements if they had gone live as is. It used synergy between a light ranger splash and TWF, and between kensei and monk. Any numbers here will be taken from the toon I used, however that toon have access to EE gear from lama, but on the other hand the items aren't really setup optimally, and there are lots of room for improvement (for instance I'm thinking that using epic diabolist robe is clearly not the best armor to be using). Also, the only tome the build is currently using is a +2 str one, so all the stats could also be improved if I actually had used better tomes.
Fighter 12/Ranger 6/Monk 2
Stats (32 pt):
11 Str (or 10 if you feel like using a +3 str tome)
Ranger Automatically gives TWF, iTWF, Precise Shot, Manyshot, Bow Strength and Rapid Shot. The build currently isn't using manyshot too much though.
9 Base+7 Fighter+2 Monk = 18 feats
Dodge, Mobility, Spring Attack
WF, GWF, WSpec and GWSpec: Slashing (could also go pierce if you prefer shortswords to scimitars)
Improved Critical: Slashing
Adept, Master and Grandmaster of Forms
And then you have 4 feats to do w/e with. Personally I was just leveling quickly, so didn't really think very much about what to take, but I personally ended up taking Magical Training (for cocoon), Toughness (more hp never hurts), Quick Draw (had no clue what to take at that point, and figured I would be using quite a few action boosts). I don't actually know what the last feat is, as I can't find any more in my feat list, but might just be another toughness. Power critical or great ability (dex) might also be decent options.
Using the Halfling, Kensei, DWS and Tempest trees.
First 2 core abilities (+1 dex, +1 all saves), as well as 1 cunning and 1 guile (7 points total)
One in all of the arrows leading up to one with the blade. I also grabbed 3 ranks in contemplation, 2 in improved dodge, 2 in crit attack and 2 in crit damage, and 2 extra dex. I also grabbed the level 3 and 6 core abilities. (Spent 43 points total) (note - I didn't take the +8 str boost, since I do not see any need for it, since I'm always using dex for damage)
Lots of options here, but to me, 3 ranks in improved defense is the most important (deflect arrow with 2 sec CD really feels like it adds up). Also grabbed a rank in sprint boost, some TWF damage, and obviously the level 3 and 6 core abilities.
Fairly straightforward - 3/3 in stealthy for 1d6 SA, 1 rank in damage boost, level 3 and 6 core abilities (exposing strike is really good, especially when soloing).
I used shadowdancer as my epic destiny, 6d6 SA is really good when you have a way to get it to work most of the time, and it also offers more survivability, which never is bad. Twisted cocoon, sense weakness and GmoF 1.5W when using weapons that center you.
Now, for a listing of what I actually have that makes this build fairly nice:
Currently sitting at 46 dex, which helps a lot with ref save, AC and damage.
Full GM stances, and centered, using dual scimitars (or some other light weapon). This allows the use of GM wind stance for 10% doublestrike and no dependency on haste or the likes, or lets you use GM earth to get +30 PRR and the crit multiplier (assuming you twist the GmoF earth stance thingy or are in GmoF).
90% offhand strike due to tempest
Fairly good executioners strike DC whenever it procs (7 base+7 charges+25 level+18 dex=57 - and you could easily get a higher dex than me with some tomes, etc.)
10d6+13 SA combined with exposing strike to make you able to abuse it, together with your already really good attack speed.
Lots of defensive abilities, in the form of dodge (was sitting at 20% with 7 shadow charges), 25% incorp, can grab blurry, and even ac shouldn't be too hard to buff up to decency (while it won't help you a lot, it shouldn't be too hard to use for decent benefits either)
Manyshot if you ever feel the need to use it.
Also, if the current really high AP costs to get stuff gets reduced the build would only get better, as it could then get say more small damage bonuses from tempest, or some PRR, etcetc.
EDIT: Realised that it's probably worth it to take the power surge in kensei, not to get the actual surge, but because of the +1% doublestrike you get, and that you weapon can get another +1 from the 2nd ability or w/e. So dropped 1 seeker, and grabbed the power surge and another 1% dodge.