shaves 1% to 4% off the +Effort scale across the board— despite the HY same finger bump—against the Thumb H layout on klatest for English prose. Swapping the pinkie Q and J further reduces the klatest score a hair.
Still old school, I am reluctant to give up the thumb Space key but this simple key swap warrants further investigation and trial..
while the +Effort scale improvement is largely a wash, more than any perceived improvement in finger metrics are the more comfortable I digram finger rolls.
With I on the home row for Thumb H, the outward rolls for EI AI OI UI are much more noticeable. On Thumb I all I digram combinations are equally comfortable and easily overshadow the same finger bump of the HY digram.
The Q J swap is not as clear cut which is not surprising given the sliver of improvement on klatest. The QU digram comprises 75% of all words containing the letter Q but J is the more common of these two low frequency letters with triple the number of words containing J digrams. Ultimately, the QUE QUA QUO trigrams won home row placement for the Q but others may find the J placement more to their liking..
Sitting amongst the top of the klatest rankings, it is difficult to envision a layout that will feel more comfortable to these hands— though, that’s what I thought with Thumb H :-)..