The rubber on this band begins to crack after a few months

The Band 1 also does not have a replaceable band however, but the rubber is much more durable.

it goes from the stiffer / thicker rubber over to the thinner and softer

The rubber will crack and you will have wasted almost $200.00.

Rubber made band cracked, called to inquire about repairs, Microsoft advised this service not available

and the rubber split while doing push ups

Negative: The band is made of a vulnerable rubber material

Therefore parts of the pcb go even into the rubber band and right beside the display the rubber is also stiffer and thicker