When you are in the pronouncable arena the quality of the letters is secondary. What matters is the sounds, are they pleasing or sound important???
I was looking at some pharmacutical ads this morning - one five and six letter pronouncable after another. Bet they like them because the trademark is stronger and they can go to town with branding.
All of that said, I really wonder about what some people consider pronouncable. And get this - Acronyms are the basis of short domain end user sales in my opinion (I get a lot of flack about that from the pronouncable people). Would it not be the best of both worlds to have a pronouncable domain made with good letters?????
Remembering that this is an area where there is a lot of disagreement, I would set up the chart this way for English:
The worst letters: Q X Z Y - (most accept this group (again, we are talking about English) but some differ on the order)
Second Tier: V U K J W - (there is a hard line in people's minds between these 9 letters called bad letters and the other 17 called premium letters. There is no greater frequency difference between W and H than any other adjacent letters, as far as I know, but the superstition is strongly placed and we have to live with it.)
__________________________ HARD LINE ___________________________
Low premium: H F O I G L
Mid Premium: R E N B D P
High Premium: T M
Top Tier letters: A C S