Maltron is available with a trackball between the left and right hands.
Ah, yes... I forgot about the fact that Maltron has a trackball option. I'm not too sure that'd be any more convenient than a trackball to the right of the keyboard though. When I compare hand movement to the middle of the keyboard vs to just right of the keyboard, it feels about the same. I guess it would allow you to have both a mouse and a trackball both within short reach, which would be a plus.
Maltron split is more appropriate for old-skool typists like me.
Given that the general design is so similar between the two split wise, I'm curious as to why you think the Maltron is more appropriate. Unless you're just referring to where they stick a given key by default?
I think that Maltron has more thumb keys.
Maltron does have one to two more thumb keys. (Depends on whether you have a double width key turned into two smaller ones.) That said, I don't think the thumbs are really that great at fine motor movements to hit the smaller keys. Maybe it's just me, but while stronger, my thumbs are nowhere near as effective as my pointer digits on hitting varying small locations without fatigue. While I can hit the 4 main thumb keys on the Kinesis without any problem, the smaller ones just don't feel that natural in comparison. Even if the Maltron is better in that sense, I can't see myself really wanting to use my thumbs for small keys. (Even when positioning my hands for best comfort on hitting the thumb pads, the finger movement needed to actuate multiple smaller keys just feels awkward.) Given the fact that even the Maltron relegates the smaller keys to lesser used things (home/end/arrows/etc), I think they agree. Note that I have large hands though, so perhaps other people would have an issue even using the main thumb keys on the Kinesis.
Personally, I think the Maltron's separate Num Pad is a disadvantage, as you have to leave the home row (also for escape, etc). Non-tactile F and J key caps make this worse. Lillian Malt was a typing instructor and designed the general layout in the early 70's; it is geared more towards secretaries than programmers. That said, Kinesis puts square brackets into unusual positions.
I agree with the numpad assessment. As for the brackets on the Kinesis, I personally find the arrow placement to be more unusual and downright confusing to use. Thanks to the programming ability of the Kinesis though, you can fix any placement problem easily. For instance, I've modified the embedded keypad keyboard level so that when toggled, ESDF become the arrow keys. Since I also have the foot pedal attachment, I can toggle that keyboard level hands free no less! There are too few keyboards out there with that level of flexibility.
You can probably badger Maltron into using brown Cherrys instead of blacks --- they are custom made. The Maltron case is made using vacuum forming, so it's a bent plastic sheet. MX-keys are snapped into this sheet and I assume the keys are basically individually wired to the controller, not PCB mounted (which would be difficult because of the 3-D design). I think the light construction is actually an advantage, as bottoming out forces are readily absorbed by the case.
Yeah, I imagine you probably could get a Cherry brown version of the Maltron, but I question why they use the blacks to begin with. Given the purpose of the board, it would seem that browns would have been the default. Eh, chalk it up to differences in preferences I guess.
Maltrons are supposed to be hand wired, but I think that's more of a "we're adhering to our history" or "don't fix what isn't broken" sort of thing than anything. The Kinesis is PCB mounted, and they don't seem to have any problems with the curved design. *shrugs* I'll give them credit for doing something the old fashioned way, but I'm a realist, and I don't trust a person wiring things by hand any more than a machine soldering to a PCB.
Ultimately, I ended up very satisfied with Datahand mechanics.
I'd like to try a Datahand at some point, but given the price combined with the fact that the company is all but dead, I'm weary of investing into one.
They do support their keyboards long term though and they can repair / refurb old keyboards in the interests of ongoing support.
For what it's worth, the Maltrons have a 1 year warranty while Kinesis have a 2 year warranty on their keyboards.
Also, while I know I'm coming off as almost anti-Maltron in these posts, I really don't have an axe to grind with them. I just see them as having stagnated. If they put half the effort into improving the design as originally went into inventing it, I'm sure they'd beat the Kinesis hands down. As it stands though, I'll stick with my Kinesis without any regret. Heck, I'll probably end up buying another Kinesis to hack into two eventually if they don't come out with their own split version.