Most stable TMOS version

11.6 - Personal bad experience with HF4. Had a recurring memory leak incident and an engineering hotfix did not help. However, many companies use this version in production environment, and have no complaints. I believe it comes down to complexity of configurations and the luck factor. 12.0 - No bad experiences, but I'd categorize this version as risky. A typical consulting firm would not recommend opting for a new major release which is only 6 weeks old. This is not an issue with F5 or this particular release, but I believe this risk factor applies to any "fresh from the bakery oven" software of any vendor. Perhaps 12.0 is worth a serious consideration a few months from now.

Thanks a lot. I think I will go for 11.6 as it's simple config. And trust me, I am not fan of putting newest versions in production right after release :-) Too long in this business to be test bed for infancy period :-) Piotr

Can i just say that I'm in total agreement with Hannes and this is my order of preference to my customers. To add, however, I am only recommending 11.6.0 if there's feature required in this release, otherwise it's 11.5.3. One other thing to note is the End of Technical Support dates, this is another reason why 11.5.3 is more tempting than 11.6.0 as this runs out in 2017, but 11.5.3 has support till 2020. My 2c

Thanks Nathan, still it seems that 11.5.3 is the winner :-) I assume with HF2? Piotr

Yep