I'll reply here vs replying to all the PM's on the comparison from the M8 to the Pro.
First off, these sleds are set up completely different. The M8 had a bigger 2871 Tial turbo with a .86 compressor housing. Boost was 12-13 lbs, going as high as 15 lbs a few times. Gearing was tall at 59/61 with a diamond lite drive. I was planning on dropping down to a 55/65 or putting on a 7 tooth driver with an X3 track, but I sold the sled before doing so. The M8 was very fast and it was an excellent chute climber. It pulled hard in the top end, sidehilled anything and was always reliable. It used a lot of fuel and oil.
The Pro has the 2860 GTX Tial kit with air-to-air inner-cooler, 7 tooth avid drivers with an X3 3 inch pitch track. I'm also running a belt tensioner from Fire-N-Ice. I've added tunnel reinforcements in the footwells from Kurt's Polaris and Dan Adams bumpers front and rear. Originally I had planned to install the 2863 Tial but Jared at BD convinced me to opt for the 2860 based on my elevation and riding style.
The M chassis and the Pro have very similar mannerisms and require a lot of the same rider feedback. The transition took no time at all. My setup on the Pro is awesome in the trees. My boost is set at 10 lbs at 6000 feet and it has adjusted to as high as 12.2 at 10k feet. The Pro is amazing in tight sections and the throttle response is insane. I've never had a bog or hesitation anywhere. The combo of the GTX 2860 and the X3 is a riders dream. This setup allows me to be much more playful in tight areas than what the M8 would.
The Pro doesn't have the top end kick that the M8 did, but the Pro stays on top of the snow better and carries speed up the big chutes. I had to eat crow as I was worried that the 2860 setup would leave me wishing for more when in reality there isn't anything that I'd do different from my current setup. The Pro sips fuel and I add a little oil to each tank.
Overall, the Pro is a more well rounded setup. It's also 4 years newer and the BD box of today isn't anything like it was a few years ago. I still prefer the feel of the M8 in the steepest side hill situations. Call me crazy
. The M had a better balance in the real steep stuff and I have to stay much further forward on the Pro to keep the backend from washing out.
I can seriously say I ride with about 20 different Pros that run the same setup that I have and the only issue I've experienced in the last two seasons is a few sets of A-arms and I've seen two belt-drive belts come apart. The highest mile 2013 I know of is at 1600 miles, all trouble free. This BD setup is pricy, but it works and I haven't experienced or seen any issues on the hill and the performance is outstanding.
I realize I'm posting in the Cat section, so I'll leave you guys with a little reassurance in that I know of MANY TM8's with 6000+ miles with good maintenance that are still ruining strong. That 800 is an amazing motor.
Pray for snow. My Pro needs more powder to shred!