Kansas Racer,
I think the Bloody Knife is worth the additional $60 over the regular Knife because it has titanium turnbuckles ($6), the right tires for racing ... purple front/ gray rear ($40 for Jacos), rear lowered aluminum bulkhead ($45), aluminum screw kit ($20), fake transponder (not really necessary), plus you get some cool anodizing (not necesary as well). Unless you had the tires and the aluminum screw laying around (the car is kind of heavy compared to a 12L3) it is a pretty good deal.

I personally bought the regular version even though the Bloody Knife was available. Looking back, I should have went with the Bloody Knife. If you are looking to have a top of the line "Factory Team" type car, the Bloody Knife is great. It was my first 1/12th scale in a while so I need to get used to the car and tuning it first before worry about trick upgrades. 1/12th scale is really fun.


carpet_killa,
The IRS diffs use a fiberglass axle and locking D-rings from a Losi XX. You don't have to glue the rings and they don't slip because they are keyed. Plus it includes a nicely machine left side hub as well. My Carpet Knife came with axle and diff hub but not the nicely machined left side IRS hub.