I have been running RasPBX myself now for several months, works very well. I just replaced my Raspberry PI B board for the B+ model as it is 30% more energy efficient! :D Can be a real money saver!
I was paying £9.60 a month to Voipfone for three extensions, one UK geographical number and call barring. Between my OBi202 and RasPBX I now pay just £2.40 a month. :thumbup:
Anyway... Nothing wrong with the 1xx series ATA's, if it does everything you require then why spend any more right? I will say this though, there hasn't been any firmware updates on the 1xx series for a while now! So no new features are likely to be added, there are no known bugs in the latest firmware as far as I know so it should be rock solid stability wise.
The 2xx series as you know does cost more but... you can however do more with it configuration wise. What you need to find out is will you want or need these extra configurations. Even the simple things like being able to adjust the length of time the device pauses before dialling a number not matched to any dialplan string is handy! The default is 10 seconds which can feel like forever when waiting for a call to connect.
If it was me and I had the extra cash available then I would definitely pay the extra and go for the OBi200 with OBiLINE, it's going to be supported for longer; the 1xx series is a few years old now.