Here's another recent thread where I briefly touched on this subject, along with more good info from others about pellets & smoke output in general:
MAK Smoke Output & Pellets (split from MAK 2 Star review)
Here's what I know about charcoal-blended pellets.
At one time, about 6 years ago, BBQr's delight offered a charcoal/oak mixed pellet, but as far as I know they were soon discontinued.
Lumber Jack has their "CharBlend Hickory" pellets, which seem to give me a bit higher grilling temps in our MAK with the new FlameZone, set on "GRILL/High" mode. High BTU's, good flavor, and low ash.
Here's the caveat; the only way I know to get them at a decent price is to include them with a bulk order. Otherwise they are pricey ($25 per 20 lbs on Amazon)!
PelletPro also has charcoal/oak blended pellets (never used them), but are also quite pricey ($29.99 per 20 lbs).
So... unless you want to pay a premium price, or can get those pellets in a bulk order to bring cost down, your best bet is to stick with
straight 100% oak pellets. Oak will give you the best overall BTU's and lowest ash.
Hope this helps!