It's not quite two months in, but I said I'd give an update on the Elecom Deft Pro after some use, so here I am!

Bad Stuff

Bad news first...

Initial Adjustment Period

I'm not gonna lie, the initial adjustent period on this was rougher than I expected. This trackballl was extremely uncomfortable for the first week, and not particularly comfortable for the following 2 or 3 weeks either. Expect to take some time getting used to this.

Form Factor

My biggest complaint is probably that it's too small and too light. It should be 2-3 times heavier in my opinion to stay put. And I guess I should have guessed it from the name, but it's really small. Almost too small for my hands.

Ergonomics

I'm not sure what it is with Elecom, but a lot of the angles make no sense to me. "Straight" as measured from the USB port puts the angle for the main ("left") click button off by like 5-10 degrees. So I always want to have it off center, but that's challenging on my admittedly small keyboard tray. I'm also not really sure whose hand they designed whatever is further right than the right (alt-right?) button for. I never planned on using this or the middle click button anyways, but they are just weirdly positioned. The forward and back buttons are also weirdly positioned.

These were also weirdly positioned on the HUGE, but the Deft Pro seems worse. It's exacerbated by the fact that the thing weighs basically nothing, which is not a positive thing when you're trying to poke it at weird angles that will definitely move it on your desk. And I'm not sure what the other weird button and switch are closest to the hand rest and on level with the left click button, but they are in such weird positions I will NEVER use them.

Scrolling

Oh my, this was a huge (lol) adjustment... The scroll wheel is SO CRISP! I also kinda hate it, since even at max speed it's way too slow. I literally reach for my MacBook trackpad any time I want to scroll fast through a large document. The scroll wheel is precise, but it's also kinda terrible IMO. And unlike the HUGE where you could sort of scroll horizontally by awkwardly nudging the wheel up or down, the Deft is so tiny and light, and the wheel is so stiff, that you can just forget even the most awkward horizontal scrolling. Use your laptop trackpad for this.

Good Stuff

I'm sure I sound VERY negative at this point. And I really do have a lot of bad to say about this trackball. But I'm still using it and actually do have some good things to say.

Ball / mouse behavior

Honestly I don't have any complaints about this. I saw some very polarizing opinions about the ball not rolling smoothly but I have had relatively few issues. It's not sticking or anything for me and feels pretty good overall. My precision feels slightly better than with the HUGE.

Buttons actually working!

The reason I replaced my HUGE was the unreliable buttons. Maybe my HUGE was a lemon, but the Deft Pro has been great. No missed / duplicate click events. It really just works.

Overall

Well, I'm still using it ;) Several things annoy me, but it's better than my HUGE. The other trackball I considered was a Kensigton. I might still buy one, but only after I either:

1. Replace my Kinesis Advantage2 with a smaller keyboard with fully disconnected halves (I'm eyeing the Advantage360 or one of the Cosmos Keyboards designs), or...
2. Get a bigger keyboard drawer.

Overall it's not a bad trackball, and you might even like it if you're primarily working mobile. But I use this at my large desk and I have a few complaints. Despite my ergonomic complaints, it's still better than most mice, and your experience will probably be better than mine since my hands are large enough to make serious piano players envious.