Not trying to flamebait here, but genuinely puzzled - what is possibly so great about the N900 versus something like a rooted Nexus 5?
I see comments about cyanogenmod, etc. being a bit unstable - but comparing it to the N900, where very few people actually cared about building the OS ? The next version of the VM - ART - is nothing to sneeze at as well.
I'm not sure if you know, but when you install cyanogenmod (or one of the hundred different ROMS that people are actively developing on xda-developers), you get a Google free operating system. There is NO integration with Google. It is only if you install the "gapps" package, that you get the whole google shebang - play store, services, etc.
As a hacker friendly phone, I can develop on the N5 using Python, Golang, Scala, C#/Mono, QT, etc. - is there a usecase at which the N900 blows this out of the water ?
The only valid point I can think about is the keyboard - yes, it is a paradigm shift. But for daily use, smart keyboards like Swiftkey, Touchpal (
pure open source) will serve you very well. For your developer needs, connect a monitor through HDMI/MHL and use a microusb
adapter .
You have a first grade terminal emulator, IRC, low power bluetooth, built-in VPN + tethering - I would argue much more suitable for the developer than the venerable N900. Did I mention quad core processor, GPU and 2 GB of RAM with a brilliant display ?
If you want, you can install
other OSes on the phone.