I recently come across these and am thinking as an alternative to my MX Revolution fow when I am not gaming.
I quite like the sound of the new optical ones, but have heard that the bearings are now plastic rather than the old metal. If the balls are the same size as the older ones (2.25" i think), would it be possible, do you think, to butcher the 2 together, or would it be too much trouble for little/no gain?
I think you will have little luck combining these two, they have very different mechanics. The older Turbo mouse was sort of quasi-optical, the ball's turning made the donut shaped bearings it rested on (one for H and one for V) turn, and these had black lines painted on them which an optical sensor picked up. This made the ball easy to replace with other round things of approximate size, 8 balls from certain gauges of pool tables worked reasonably well. Although the bearings were made from metal, the lines on them would scratch/wear somehow off over time, the ball would wear a grove in the middle of them, and the bearings would get all kinds of hair and strange things caught up in and wound around them. This gunk would eventually get in between the bearing's painted surface and the optical reader, making movement erratic. You could clean them (had to regularly) but eventually the casing would get loose, and the body screws were only meant to come in and out of the plastic so many times, etc.
The new model is more of a true optical system, the ball itself is sparkly and there is a single sensor area in the bottom that reads the sparkles somehow to register movement. So you cannot replace the ball with just anything that fits in the hole
Although the overall construction of the newer model is definitely cheaper feeling, in practice the new design seems more durable. You don't lose accuracy as the bearing fail/lose their lines/get cruddy. Yes, the ball now rests on tiny cheap bearings of a material that doesn't look like metal to me, not sure what it is exactly. However, these no longer really matter so long as they allow the ball to spin, which they seem to do really well. The action on the ball is much lighter and more nimble than the original. This may seem kind of gross, but I actually noticed that as your hand "funk" builds up in the bearings, they don't even turn so much as just let the ball slip.. i clean them regularly but it seems impossible to keep them very clean. maybe collecting hand grease was part of the design.
Sorry to ramble on. I think you will enjoy either the older or newer model, they are both great devices. I went through 2 of the original turbo mice over a span of about 4 years, very heavy use. One failed when the bearings just worn down to the point where the action had too many dead spots to deal with. The other had cord issues where the wires came off the board and i soldered them back (poorly) on so many times that there just wasn't much left to solder to. I've owned my current generation for over three years and it is even better than new.. these definitely need a break in to be smooth (maybe need proper grease build up? i don't like to think about it heh).
One to avoid is the "Kensington Turbo Mouse Pro USB Trackball with 6 Direct Web Buttons USB for Windows or Mac - 64214" as seen here:
http://www.amazon.com/Kensington-Trackball-Direct-Buttons-Windows/dp/B00006B8NSIt was made in between the good old ones and the good new ones, apparently still for sale. I used it for about a year before the current design came out. Maybe I got a "bad one" but it never worked smoothly for me, never just felt right like the others. Also the 6 extra buttons are useless and the scroll dial is in a ridiculous place. The scroll dial on the current model is excellent after break in.
well, again, i've rambled more than enough, good luck and hope you enjoy a kensington trackball as much as I have.
one more thing - for some types of games, the kensington will give you a unique advantage. Because the ball has decent mass, you can give it a spin and let go.. with a little practice this becomes natural and accurate. its been a while since i played fps type games, but back in the days of Descent I could do tight flips and spins that no mouse user could come close to
