My guess is that it would be very difficult to interpret the data you get. When you program, you spend most of the time thinking, not writing. I guess you could, to borrow a programming term, "trim" the time interval around every word you type. A second possibility is to track specific characters and compare time between the character before it (and weed out the anomalies). Brackets would word fine, because they're typically at the end of a word.
A second possibility, is that you could make a typing test for (similar to the ones online), but for code. The program could check which layout is active and store your results in a database. The results could be compared between layouts, especially with focus on keys that differ between the two layouts. Keep in mind that it takes a while to get used to a layout, even longer to become proficient, like you are with DE.
I switched to UK layout a few months ago, and plan to further switch to US when I get my ANSI keyboard. The latter move is simply to have more alternatives with both keycaps and keyboards. I make less typos for special characters like brackets. The key placements are just so much better suited to programming. I've made a custom layout for זרו that I access with ALT GR. Alternatively, you can just switch between the layouts when you need to write something in German. I personally found that to be confusing, and I often forgot which layout was active.
