2012 went in a direction that stopped some common problem areas from being configured, however it also removed some functionality that a lot of customers liked and as such some things were re-introduced in 2014. What this means is that the recommended upgrade path for customers on versions of BE prior to 2012 is to avoid 2012 and go to 2014. (where supported)
Because BE 2012 insists on one job per server, it is very difficult to manage tapes if you are trying to get more than one server on the same tape for each day, as you have to specifically setup your jobs so that the one that starts first overwrites and then subsequent jobs append. However if a library is involved you also have to somehow restrict all the jobs to one tape. BE 2014 brings back the ability to handle multiple servers in one job which helps massively with this process. Which might mean that BE 2014 is a better fit for what you are trying to achieve.
Note: how Backup Exec handles tapes for both Appends and Overwrites has not changed across any of the BE versions but the single server per job model in 2012 is known to cause media selection and rotation issues with relation to tape handling.
