I am in a similar situation as the thread's OP, looking for a GNU/linux portable machine. For me telephony functions are mandatory since I would like to avoid to carry two different devices for 'quick' tasks on the move and I need my laptop for heavy computations, bringing to three the number of devices always with me.
Currently I am looking at the Pyra with 3/4G module wondering if this will work fine with a BT headset as a mobile phone. Neo900 is interesting as well but I am afraid an updated browser will be a dream there as well, specially due to not enough horse-power and that is the biggest concern for which I still did not byte the bullet. Having a 'free' phone is really tempting, though.

I recently revamped my n900 after two years on Windows Phone because of taskwarrior, which I found great on the desktop (on the laptop I use both Linux and W10->cygwin) and perfectly suited to my workflow after two years looking for a good 'ToDo' app. Succesfully compiled for my N900, I have now a great tool acting as my own agenda and my phone at the same time. On n900 I am missing only a 'real' offline navigator application and an up-to-date browser, otherwise there will really not be any drawbacks for my use case. Do not forget we are talking about a 7 years old phone, now! What a great device the Nokia team designed...

BTW from a 'work' point of view I admit I found WP8 being a great device/system. The Surface is a great device as well, my wife being less geeky than me is going very well with a WP+Surface combo.