What are pros and cons of upgrading from SR3 to SR4

[#1]

The main reason that we are upgrading is, When using SR3, users are not able to access dashboards from iPads(iOS5). I have gone through the various topics and discussions related to similar issue and found its problem with SR3, when we contacted qlikview support, they suggested to upgrade it to SR4. But We are not sure whether its 100% performance environment.

Have you come across any issues?

[#2]

2 frequently encountered issues are:

1) User CALs are denied on document.

2) Binary load aborting while loading.

3)

just post a brief detail of what you encountered.

Thank you