Although I cannot say for sure, but I have not read (here and xda) of anyone claiming that newer versions are unlock-able. I have read of a few people having trouble unlocking, but that may be due to other reasons like computer setup, drivers, misreading instructions, etc.
Off topic and to address your other question, I am very impressed with this phone. I came from the LG Marquee (which was a solid little phone), and the Moto G is quite the step up in specs and performance. It runs basically anything I throw at it with ease. Only being 3G does not bother me, as I don't use that much data, and 4G is still catching up in my area. (In my opinion, people should really look at what they use their phone for before bashing the Moto as only 3G.) My calls are clear and crisp.
Battery life is good, and some would even say great.
I have the 8 GB (Boost), so the storage space is a little tight, but I use use the
Mini MicroSD Card Reader by Meenova with a 32 GB class 10 card. Works great for storing music, movies, and all of my backups. I keep it on my keychain, so it is always with me. It is also very unobtrusive (as least to me) and does not interfere when using the phone.
I would call it a "budget phone" only in price.
Hope this helps...