I have a love/hate relationship with my racks like yours.
I love the usability of them and even the looks are pretty nice but I HATE the poor heat distribution I get from them!!!! I recently hooked up 2-3 dimmers on each rack to have a bit more flexibility with the whole heat rising issue but that only helped a bit.
I am currently working on a new design that I think will be a great way to incorporate the benefits on the lidless racks with the stable and reliable heating of under belly heat. I'll let you now how that project goes.