I was once interested in the Ctek too, but ultimately no smart charger can do what its marketing team claim it can do.
A regularly deeply cycled deep cycle battery has different requirements than a starting battery mistakenly depleted.
As always, never believe the full charge indicator light. this does not indicate that the battery is full, merely that the charger has decided to stop applying absorption voltage prematurely, just like the lawyers insisted.
As far as 8 stages, I wonder what miraculous stage the marketers will come up with next. Equalization and destratification are such impressive terms that going much past 'conditioning' is starting to blur the attention span of the average reader.
I propose a 9 stage charger, with the ninth stage being: super double platinum sulfate blastoid regimen, guaranteed to restore any battery back to and past its original capacity.*
* only effective with extra 200$ donation to Nigerian royalty website.