I know this an old thread, but this might be the most useful discussion I've found on the web comparing Maltron vs. the Kinesis Advantage. I am currently in possession of both (I will get rid of one), so I would like to contribute my bit to anybody that stumbles upon this thread.
After using both alternatively for a few days using the QWERTY layout, I must say that I prefer using the Maltron 89 series. Here are the strengths of the Maltron in my opinion:
Thumb keys. I prefer the depressed position of the thumb keys on the Maltron. The 89 series makes better use of these thumb keys than the 90 series Maltron or the Kinesis Advantage. The depressed position of the thumb keys compared the raised position of the Kinesis makes a difference for the farther away, smaller thumb keys and caused less hand strain with heavy typing.
The shift keys. The Maltron has those big shift keys, while the Kinesis Advantage had those tiny shift keys. When switching between the two keyboards, I made considerably more mistakes with the Kinesis. The pinky is not the most useful finger, so it helps to have a big shift key. But I've always had trouble with smaller shift keys.
Space between keys. The Maltron has more space between the keys and I find that very useful for reducing mistakes and not double typing. I think the Maltron is better suited for people with bigger fingers that always have trouble double-hitting keys.
Less concave shape. I'm not sure if that is the right term, but the Kinesis seems to have more curve to it. That made my fingers feel crowded in that typing position. Didn't like it. Plus that bottom row of the Kinesis was very uncomfortable to use.
F keys. I don't use these much, but those rubber pieces of crap on the Kinesis really need to be upgraded. And I can't imagine it will raise the price of the keyboard that much.
The Alt/tab combo. This has been criticized many times on the Kinesis Advantage. The location of the Alt/tab is wretched. Maltron did a good job putting the tab in the thumb keys.
Another perk with my particular used Maltron is that the parenthesis, brackets, slashes, and carrot things are on separate sides of the keyboards. This is much more useful than the normal location on any keyboard, and on the locations of the Kinesis. I also don't understand why Kinesis puts two backslash keys on the keyboards. What a waste.
After tearing apart the Kinesis Advantage, I will list what I like about it better than the Maltron.
Programmability That certainly is nice and a huge plus. I can move keys around like those poorly placed arrow keys and use different key layouts. If I don't like something on the Maltron, tough, I am stuck with it.
The big Backspace/Delete keys I like these better than 89 series Maltron's smaller keys on opposite sides of the keyboard.
Cherry MX red keys I preferred the Cherry MX red key switches on the Kinesis rather than the more resistant Cherry MX blacks on the Maltron. However, the harder to hit Cherry MX black keys do reduce mistakes because I can't type as fast.
Overall, I found the Maltron to be a more ergonomic design and more comfortable to use. I preferred the position of many keys, and the feel of the keyboard while using it. I made less mistakes with the Maltron. The Kinesis Advantage does have the huge advantage of programmability and a much lower price. However, I obtained a used Maltron for about the same price as the Kinesis, so price wasn't as large of a factor. I would have a lot of trouble justifying the purchase of new Maltron considering the rumored programmable Maltrons. I have an email from a Maltron representative say they are testing a prototype of a programmable keyboard at the moment. Should be interesting.
I thought that I would follow up on my original post now that I have been using both keyboards for a couple months nows (Typing on the Kinesis Advantage at the moment). I used the Kinesis at home and the Maltron at work, so I got a pretty good feel for both.
Both have great ergonomics, and I enjoy using both keyboards to a great extent. For the Maltron, I preferred the ergonomic design, the design of the thumb keys, the integrated trackball, and the center number pad (great for navigating with the proximity to the trackball). For the Kinesis Advantage, I preferred the programmability, the Cherry MX Red or Brown keys, and the lower price tag. I got the Cherry MX Red, and I am happy with the ease of typing as compared the the standard Cherry MX blacks on a Maltron. I am becoming really light on my typing with these Cherry MX reds.
In my original post, I had some complaints about the shift keys, Alt/Tab key distance, and the spacing of the keys on the Kinesis, but the ability to reprogram any of the keys alleviates those problems. Also, I think the reason that I felt like i had more space with the Maltron was because they use spherical keys. I ordered some spherical keys for my Kinesis on the group buys, so it should be interesting to see how the Kinesis feels with all spherical keys for all the letters.
After using both keyboards for a couple months, I've discovered two things:
1. The style of mouse caused more pain for my hands than the keyboards.
2. I would love to have a split, two-piece, programmable keyboard with mechanical switches. I guess I have to wait for the Ergodox.