My PKL files should handle Vietnamese just fine. I can type the name of Thích Nhất Hạnh properly, for instance. It's a matter of having the right dead keys defined. However, if some accents are very common then please let me know so we can create a more convenient layout. Chech out my Locale topic (link from my signature) to see examples of these.

I have AltGr+' as my acute accent, etc (see my Colemak[eD] topic). Accents in PKL stack, so to type ấ I'll usually type first AltGr+' (´), then AltGr+6 (^), then the a. But this is using my PKL files which define dead keys well. The dead key tables need entries for every possible combination. So it'll have another entry for pressing 6 before ' to produce ấ, and another two for Ấ. All in all, that's a lot of entries I've made! :-)

Using for instance the PKL Tarmak, you'll only get "VirtualKey" layouts which merely move the keys from your OS setup without adding further mappings. It's only in the full Colemak that I have made the Colemak[eD] mappings that include my dead keys.

As mentioned, if you use accents/diacritics a lot (and Vietnamese certainly does!) you'll probably want to move some of these mappings from AltGr to the more easily accessed bracket keys. My primary targets for locale layouts are the bracket keys and the VK_102 key on ISO keyboards, as seen in my Locale topic.

At the very least, I'd move the ^ dead key to an accessible place, and maybe horn ( ̛ ). Maybe the acute and umlaut accents are okay in my setup; I like hitting AltGr with my thumb and ' or ; at the same time. But since it happens so much in Tiếng Việt, maybe they should be moved nevertheless.

Your Unikey IME seems like a compose table based method. That may be optimal for Việt, and also what you're used to. So maybe that's the best way anyway. My layouts are mostly for people who don't have a special IME. If Unikey is active, I suppose it'll be difficult to type other languages? For instance, typing a then s should produce 'á' in Việt but 'as' otherwise! If I understood you right, that is. If so, then one little advantage of my way is that you don't have to switch languages while typing mixed text.

It's probably more efficient for Vietnamese anyway, so just keep using it!

However: I guess "everybody" is using something like Unikey then? Do you think that anyone would benefit from a Colemak[eD] locale version for Vietnamese, or not? Because if you think people need it, we could make one together.

The results on this thread are impressive. I'm just making the transition from Qwerty where my best typing speed is 52 wpm with no errors. My target is 65 wpm. I will be posting my results here in the coming weeks and hopefully surpass Tony.