I believe the Sensei is adjustable, however the Kinzu is their standard mouse and it is not adjustable. They also advise not to use software to manage it as it will make it screwy. According to their FAQ only the Kinzu has accell on the hardware level. I think what this means is that it is "calculated" on the mouse itself rather than through Windows software/programs/drivers such as Razer software for razer mice.
I suppose that may have something to do with the fact that Kinzu seems to be the type of mouse you'd toss around the pad such as like in competitive RTS gaming. Accelaration could have its plus sides then. I definitely liked it for tossing the cursor away to some other part of the screen and then being ablo to micro there, as opposed to having to drag the rodent a long way. But that was many years and many dpis ago. I could get away with max speed and max accel with a ball mouse and 1024*768 screen resolution. Couldn't really be so accurate playing RTS in HD res.
I wonder if hardware acceleration doesn't work better than software, which could be kinda interesting.
Some of the Sensei's oh-so-innovative functions with fancy names are basically just positive and negative acceleration.
Wonder if the price of the Xai will fall due to the Sensei. I can already see the XAI for little more than 50 euro in Poland.