I don't mean to criticize the choice of 5.5" because I know it's the result of several constraints, and the device looks awesome, really (and 4.5" would be too awesome for my little heart), but I think bigger size of keys should not necessarily be a goal per se. More keys is good, but fewer keys can be pretty good as well if very well integrated in the OS (like N900 key combinations + onscreen special character keyboard).

Bigger keys and more space between them is typically thought as a good thing since we are the most comfortable with bigger, real-size keyboards. However, this keyboard will most likely be used with thumbs only, and not flat on a desk with 10-finger typing. For thumb-typing, larger keys/larger keyboards means more distance to cover with the thumbs, and I don't know what is the optimum size considering variation among people's hands, but seeing that I was more comfortable typing on the N900 than the TOHKBD and mistyped keys more often with the latter, I believe it's not huge.

However, again, I understand that there are multiuple factors leading you to 5.5", and I'll still happily give you all the money I can give you.

[Edit] Excellent news TheKit. Still holding my breath for an official Sailfish license with AD included, but it's good to know that ports would not start from scratch.