I have used the Codefree since 2014, with an Accu Chek MObile as a back up and for comparison checks. The AC I've had since 2014 also.
With the Codefree, there are often noticeable differences between batch numbers, and occasionally between tubs within the same batch number.When you have a batch number that is OK, most of the tubs within that batch are also OK. The erratic ones soon show themselves and can be dealt with by doing some comparison checks, working out the average differences, and making a mental note that your levels may be a certain amount better than it shows. For this reason I log all my results on a spread sheet, every day, and make a note when I change a tub and a batch number.
The Accu Chek Mobile reads low, so beware of some very nice numbers that may not be as they seem.
Since January I have been using the AC Mobile exclusively because I got a bit fed up of a particular batch of Codefree strips. I do buy my replacement cassettes on eBay "Buy it now". (I can't be bothered with bidding wars). My last purchase was for 4 cassettes. (200 strips). I paid £39.99 with free postage. The expiry dates of each cassette is sometime in 2018. Once the seal on the cassette is broken, the life of that cassette is 90 days. This is the same with all cassettes, even if you buy from a pharmacy. I have bought dozens of cassettes on eBay and had no problems with any of them, but I always check the advertised expiry date. No expiry date mentioned, I don't buy.
I have noticed an increase in prices on eBay during the last few months.