FreeNAS suited really well in managing our legacy systems and it handled all our network flows really well, less maintenance is required on our part. FreeNAS also gave the option to switch to TrueNAS for free as now its support is limited. The major issue that we faced was with the installation as it is really complex and required lots of time. Rest all is good and FreeNAS still works well on our systems.
SLES is a good fit for running supported enterprise applications like SAP, HANA, oracle,.. We use it to run all our SAP workloads, and so far everything has worked great. All libraries are right in the repository, all documentation is correct and the support answers really fast in case you have problems.
The support window for service packs after a new SP is released is too short.
Community engagement is low.
There are times when supported packages fall too far behind and create compatibility issues with applications. The Open Build Service usually provides a way around this, though.
For the breadth of services, features and overall performance, I believe Suse Linux is a great choice for any enterprise. It still has to grow a bit in areas like online help forums and documents, but we are pretty much satisfied with our choice.
It's great for basic support issues. But it's less suited for anything that is either obscure or uncommon, and it is very hard to escalate, unless you've built a relationship with your vendor/salesperson.
Before swapping to FreeNAS, we'd been using plan old Linux servers running Samba and NFS with ZFS storage underneath. This worked really well for our requirements at the time but required a lot of administration when new versions came along, or new users had to be added or drives needed replacing, and so on. FreeNAS did away with 95% of that work and does a much better job too.
SUSE Linux Enterprise Server works well with the SUSE Manager, it really simplifies everything. We also do have SUSE 4 SAP, and the SUSE Manager is able to manage them all, even other (up to date) Linux distributions. Patching has never been that easy and the SALT integration is also working without any problems.
It allows a very small team to manage a large number of servers, due to its automation and manageability.
SAP supports it very well, making it straightforward to manage. There are also "recipes" for Oracle which has all of the requisites to install an Oracle DB; which helps with deployment immensely.
It lets us run large SAP instances in SLES on Power, helping us with support, manageability, and performance.
Support costs are high, but required for SLES for SAP.