I'm considering switching from typing on my MacBook Pro's keyboard, to a Kinesis Advantage (either Advantage 2 or Advantage360, I haven't decided yet). The question is: conditional on doing that, how will my typing speed change after 2.5 months of mostly using the new keyboard ~every day?

Over the last ~2 weeks, I took 8 typing speed tests on typingtest.com (1 Minute Test, Medium Text). Results (not cherry-picked): 57x98%=56, 58x100%=58, 52x100%=52, 50*98%=49, 58x100%=58, 43x100%=43, 47x100%=47, and 55x98%=54 WPM.
Average: 52.1 WPM (after accounting for typos).

To resolve this question, I'll take another 8 typing tests on the same website ~2.5 months after I start using the Kinesis Advantage keyboard.

Example: if my typing speed after 2.5 months averages 48.3 WPM (after accounting for typos) across the first 8 tests that I take, I'll resolve to 6-18% slower, since 52.1*.94=48.97>48.3.

Other rules:

• If I never switch, the question resolves ambiguous.

• If I switch and I give up after <3 days, I'll resolve ambiguous.

• If I switch and I give up after >3 days, I'll resolve to my best guess of where I would have been after 2.5 months.

Context:

• For the first 1-2 weeks, I might only use the new keyboard for a few hours a day to avoid being slowed down too much.

• I have relatively large hands (but not huge).

• I have a desk job, which involves a fair amount of writing.

• If I switch, I'll probably do 1-4 hours of deliberate practice to get used to the new keyboard, probably front-loaded. But I won't practice on the test website above (to avoid learning their tests).

• I already have decent touch typing technique, i.e. I usually type letters with the "correct"/standard finger (possibly my form is bad in some other way?). I learned this when I was ~12 (> a decade ago) and have been using it in everyday usage ever since. So, I don't expect a few marginal hours of deliberate practice to make a huge difference.
  

I will not trade in this market.