I have turned 3G back on. The reason is simple. With the mobile companies pushing the data traffic towards LTE (“4G). The amount of data traffic passing over 3G has been dropping at fast rate. This means that in most places using 3G for voice communication is now again option. In some high usage area voice calls might get pushed back to 2G. Same goes for areas with poor 3G coverage.
I am going to keep 3G on from now on. But I might turn it off in areas where coverage is extremely bad. But using GSM in such areas often brings better connection signal then 3G (it also because of lower frequency that GSM uses in most cases). This has everything to do with more GSM transmitter then 3G transmitters today. Why this is the case I do not know. But I do not expect it to change any time soon.