So far I see each new version to build on the prior version's success and features. There are however folk that dive deeper and write "serial numbers past 310,xxx might be better."
Then again you might find folk claim that versions in one continent are better so where to go here.
Let's try this. If the folk that sell this to you will not discuss the product, DON"T BUY!
The newly released nexus 5 (OS 4.4.2 with serial 311, xxx +) is better than the previous one (OS 4.4 with serial 310, xxx +). What do you think?
More details will be welcome!