As someone who has typed many different layouts over the years, I'll add my two cents.
The "efficiency" of a keyboard layout is extremely subjective. No one layout will every be crowned as the king of layouts. You may argue that for a given person, there may theoretically exists an optimal layout. I think that's what the CarpalX project is all about, but ultimately falls short of. I don't think its configuration parameters are sufficient to truly measure the "effort" of typing on that layout. There are so many factors, and those factors are all weighted differently depending on the person.
So with that said, you could either put a lot of effort into optimizing a keyboard layout that really models you and how you type, or you can pick a canned layout such as Colemak/Workman/Dvorak, whichever one feels the most comfortable to type on for you. I have proficiently typed using all three of those layouts. From MY (subjective) experience:
*Dvorak
- took by far the longest to become proficient with
- stresses my right pinky more than I like (especially bad when using Linux shell)
- works very well with VIM without modification
- overall an great improvement over qwerty
- preinstalled everywhere
*Colemak
- relatively quick to learn
- causes my index fingers to become exhausted rather quickly
- several common key combos are very uncomfortable for me to type
- doesn't work very well with vim without heavy key remapping
- overall a great improvement over qwerty
*Workman
- relatively quick to learn
- can feel bottlenecked when typing at high speeds (this would likely get better with time)
- generally the most comfortable layout for me to type on
- 1 key is problematic in vim (J)
- overall a great improvement over qwerty
For the record, I have also proficiently typed on one of the optimized CarpalX layouts. It was the BULPKM layout that was later replaced by the one you mention. That layout was also very comfortable to type on, but it had the same problem that I had with colemak where my index fingers were over-used and became exhausted too quickly.
My advice is to try a few different ones, find the one that is most comfortable for you and stick with it. All of them are significantly better than qwerty and you can't really go wrong with any of them.