Looks like a nice upgrade to me - i don’t have a Heat Mk I but have often pondered over it. The new screen looks to be a significant advance in terms of information and use-ability.
Makes complete sense that elektron are rationalising their button, knob and display components. Can only be a good thing in terms of allocation of engineering resources and refining their production line.
Smart users (interested primarily in sound and functionality) might wisely be tempted to pick up the now overly discounted Mk 1 machines that do near exactly what the Mk 2s do. Just like OT I vs OT II.
Given the Heat is a machine designed to add grit, old skool and vintage vibe perhaps the Mk 1 is the hipper device to have on the desk, with its more authentic dot matrix screen and quintessential round buttons!