I have the CTEK MXS 5.0
It came with a little carry bag which is nice to keep all the adapters together so they don't get lost.
The stitching on the carry bag for the drawstring has now totally come undone, I should / could get one of my daughters to sew it up again on the sewing machine. But no bother.
I also (very wisely) ordered the rubber cover for it which allows you to place it anywhere on any side and have no fear of scratching any bodywork.
Totally recommend the cover.
The charger works very well, I top up my big huge Volvo D5 battery with it, it happily charges it overnight, even if it is only a 5A charger. So perfectly adequate for an overnight top-up.
It has normal wet-cell lead-acid and AGM modes, so you can do either battery. Make sure YOU know what battery you have before connecting the charger.
As for a TimeToGo mode: honestly, when you charge overnight - which you normally do as you want to connect it and leave it for a number of hours - then a TTG mode doesn't matter. MXS 5.0 shows you when the battery is 100% charged. And the little bar graph gives you an idea as to where you are in the process.
As for main vs start/stop battery: it could be that the internal electronics also charges the start/stop when the main battery is being chjarged. A charger applies e.g. 14V to a 12V battery, the higher voltage likely feeds into both batteries. But I'm guessing here as I have the older start/stop system - where the driver uses a key
Overall I think it is a wise idea for every car owner with a modern car to have a charger and to give the battery a top-up charge every now and then. Especially when you do not drive the car a lot, as the residual power draw by all the security systems and monitoring systems will eventually drain the battery.
And the CTEK is also made in Sweden (or designed in Sweden, made in China), and is used as the branded Porsche, Lamborghini and other SuperCar charges, so the quality is acceptable as a quality OEM supplier.