Would you recommend this? I've seen an issue with both 11.3 and 11.4 (don't ask as i'll have to dig them out) so is 11.5 the best option?
If it's an option, or even preferred, then yes I would recommend getting to 11.x. It puts you in a better position for both long-term support and getting access to newer features and add-on products. It also puts you in a better place in terms of security standards support.
My personal belief is that
all sufficiently-complex software has bugs. So yes, there are issues in 11.3 and 11.4 and every other release. The question is how the issues will affect you and whether there are viable workarounds if the impacts are meaningful.
In terms of restructuring your DB, any release from 11.3 onward will have all the performance enhancements I referenced. It's worth noting that 11.3 and 11.4 have a nasty prorest bug that could prevent you from successfully restoring an online backup unless it was created with the bibackup all parameter; that bug (
PSC00317988) is fixed in 11.5 but not in 11.4.
My view is that 11.5 is a better platform for the long term than 11.4. 11.4 was only the current release of OpenEdge for four months (August - December 2014). By contrast, 11.5 has already been the current release for eight months and that will likely be close to a year by the time of the release of 11.6. That means that in the final analysis, 11.5 will have gained a much larger install base than 11.4 and will likely be better supported in the long run. And it has already received a service pack as Cringer noted, whereas 11.4 still has not.
So my recommendation is to go with 11.5.1.