What a pair! I've used the Ergo since 2018 and have yet to find an equal. The Elecom EX-G Pro is my backup for 4x gaming, but doesn't hold a candle to the Ergo in the quality department.
What's your experience in using a thumb-operated trackball? I had the Microsoft one ages ago and I remember I did eventually notice some minor aching in my thumb.
Nice keyboard by the way, though I know that the Thinkpad's keyboard is a delight to type on as well. :)