Once you take into account using the Caps Lock as backspace Colemak hand balance is about 50%/50%. The layout you're suggesting has a lot more same-finger.

I am a lefty and standard Colemak gives my left hand plenty of action.  Even if I was not using the Caps Lock for Backspace,  would the balance really be enough of an issue to justify creating a design that the main criteria is skew the balance in the opposite direction.  I appreciate the digraphs I am using in my left hand now.    ar  st  rd  pr  aw  fr  gr  ft  sp  cr  ca  br  ba  sa  as

Colemak is pretty balanced as is, and the digraphs very much make it ambidextrously sound. Plus having another layout to support would lead to less support. It's hard to have converts when you splinter and taper off into dozens of layouts. Stick with Colemak, it's awesome and it works for both hands.