I have been typing in the Dvorak keyboard layout for 22 years (since 2003). This is since before Colemak was invented, and significantly longer than I had ever been typing in QWERTY (15 to 18 years, depending how you define "typing"). Now that Colemak is a widely available, built-in alternative — it's in macOS since 2011, and Windows since 2024 — I feel that I would advocate for it over Dvorak to anyone who is considering abandoning QWERTY. I may even decide to switch to Colemak myself.

Comparing Colemak with Dvorak, it has some features which are pretty cool and definitely would be a better choice for someone coming from QWERTY today:

A big win for Colemak is that ZXCVB, QW, A, H, M, and all of the punctuations except for ;, are in the same place.
Dvorak's home row with all the vowels on the left hand is great too, but only for English.
Colemak does have most of the vowels on the home row, except for the U key. Notably, it's on a different hand than the Q, unlike Dvorak.
The changed punctuation in Dvorak is more of an adjustment, particularly for programming, when coming from QWERTY.
Colemak benefits from some improvements in finger strain and digraphs, over Dvorak. Partly this is because Coleman invented his layout in 2006, and had the help of computer analysis, which Dvorak did not have.

I don't regret my time with Dvorak. At the time that I adopted it, Colemak did not exist, and it took 5 years for Apple (and 13 years, plus a petition, for Microsoft) to make it available on non-Linux computers, without installing special software. In that time I have greatly benefitted from the improvements Dvorak has over QWERTY, and being able to use it on computers that I don't have the ability to install special software into.

I do still stumble over the punctuation in Dvorak even today, and things such as the copy/paste keys being in the same place would be very handy on a computer. So, I am considering to switch to Colemak. I wonder how difficult it could be, since I have been typing Dvorak for so long? I guess it will come down to the benefits of Colemak over Dvorak, which are significant, but much smaller than the benefits of either layout over QWERTY.

I should try it and see. That's the only way to know.

A great resource to learn about Colemak and how to type with it is https://colemak.com/. It has links to scientific and anecdotal evidence for the layout's advantages, comparison with Dvorak, and some online training. ZSA (who make my favourite, daily-driver keyboard, the Ergodox EZ) also reviewed Colemak.