The S5 is leakproof... so I'm not worried unless I flip (in which case I have bigger issues). Although its not AGM like Optima and the S6, it has the proper fit and power required. If there was a direct replacement available from Optima, I'd run them again... but it looks like the posts on the 34 will be too far of a reach and the 35 series has lower CCA and CAs.

Its all a balance of pros vs cons. Proper fit weighs high on my "pro" scale.