I drove it to an indoor range about an hour away so I could spend some time setting it up. Set up time turned out to be about a minute. Strung it up and it didn't need any adjusting. I thought the rise might be a little low but the guy at the pro shop showed me how they used to measure the right rise by winging out their thumbs and pinkies and measuring to a bottom knuckle and said I could give it a try as is, and I think he was right.
Took the bow and my existing 29# arrows to the range in the back of the shop. The first shot, my jaw literally dropped and I felt like war-whooping - the smoothness of the draw and the power of the bow compared to what I've been shooting was just incomparable. The arrow actually made that quiet laserlike "zzzzzzzzzziiiii" flight sound that I've heard from others but never mine and it punched the target really hard. Felt pretty awesome. I shot about sixty arrows back there before my draw started to get weak, which I was pretty happy with what with the biggish change in poundage. Left shoulder is a little clicky today but I was maybe death-gripping the bow a bit.
Got home and my half-dozen carbon arrows were waiting for me - will be shooting those today and can't wait to give them a whirl!
The grip on the Mamba is so slender, compared to the Polar, btw. Not sure I can even go back to shooting the Polar after this. I can't even get my hand wrapped all the way around the Polar grip, and the Mamba fits me so well it's like it was made modeled after a ball of clay I squeezed lightly in my hand. It feels pretty good. I love the way it curves into the palm, really think it's going to help me keep a straight wrist. Bow itself is light as a feather compared to the Polar, too.
Do believe I may sell that Polar and get a #30 bow on ebay for additional target shooting as I condition into the #40.
Thanks to all who have given insights and thoughts about the Mamba and all this in the last week, much appreciated!