So am I.
I am aware of and have only read various reviews and comparison and have not ridden the three stellar brands you mentioned, nor the Brose, which I also like and am very intrigued with too (Ride1Up Prodigy XC ($2350) I mentioned with its 90 nm rating, great spec's and motor cutoff ability when shifting and that may be my next ebike in continuing this low buck "experimentation". This ebike scene can be/is a semi-cheap hobby (compared to other$), it is healthy, something to do with others and fun, especially for me playing with all the mental exercising. I'm not a big believer in "buy the best always" (what is "best" anyway?). I'm still too much an ebike rookie to go all in on one $4k-$12k ebike and say it's the best. For now at least, my logic says I can have in the stable up to four ebikes for under $4500 (if I include the Prodigynot on sale) have very little invested and can sell them all off for little loss and or keep one or two. The big one for me is I don't mind improving off of something that looks like it might be a good attempt. So we'll see. Frustrated engineer in me I guess!
A lot of my motivation is price point, for sure (the two Aero's were $1,000 and the D6 almost ridiculously priced as well at $1199. I pulled the trigger on the D6 for the same reason and a lot on inference when both Espin (Aero) and Eunorau have been in the low end ebike game for a while and know their sourcing world (Espin may be a little better than Eunorau with their contacts, but there is an implication they both have good working relationships than I might have on my own. Based on what I received from Eunorau two days ago, so far so good.
The Dapu hub and early mid motors don't have a very good reputation (just reading other opinions) and though I realize I'm very much bottom feeding with the D6 and outlying in the mid drive world, I have read that the Dapu MD250 is a second generation update of an older original Japanese design and now China sourced and built motor. With the built in cadence and torque sensing, we are both on the same line of thinking. I'll let you know here shortly.