Full disclosure: I don't have an N9 (but I want one), and have never even seen an N900. So my musings may be a little abstract.

From what I gather, much of the 'out of the box' experience in both phones can be optimized - which is actually part of the fun. The criticism in the OP seems to be knowledgeable and balanced, but also it seems that already many of the raised points can be answered with some tinkering. So as a potential user and a light weight hacker, it it seems less worrisome.

This contrasts with the (in my opinion) grave situation raised by many and also by Keferen:

"and the 'fact' that the n9 is going to be the only meego device with support for the next 3 years means that the hardware like the n900 will be woefully obsolete quickly, no matter how flashy the outside of it looks. but the n900 ui will still be faster to use/navigate and android/apple phones will leap ahead in functionality."

With all due respect to the amazing community here, I do not know how this can be countered other than by tapping into an existing so-called ecosystem. This would guarantee the N9's continued relevancy. Yet with
With the Dalvik Alien and Openmobile potential having evaporated, the future does seem as bleak as painted by the quote above. It is the only thing standing between me (and many others I suppose) - and full ownership of an N9.