Brakes either bite or have feel, if you want to know a littlle more the brake action and the strength of the brake relates to the ratio of the master cylinder diameter to the slave or caliper piston. The bigger the piston surface area the bigger the force but you sacrifice feel by that I mean the brake is more brutal, not always a good thing. That is the info you need really and that advert does not give that info so you do not know what will happen to the brakes if you change the cylinder. Just changing the levers will not improve your braking but does improve how you can set up your levers so it feels more comfortable i.e the ergonomics of the system, for that reason changing levers is a good upgrade because it gives you more control.
You can increase the FORCE at the caliper by increasing the size of the caliper piston surface area = more bite.
You can decrease the FORCE at the caliper by decreasing the size of the caliper piston surface area = more feel.
A good brake will balance these so you stop in a controlled manner in the space you have to stop in.
I doubt I would bother to be honest, unless you are sure you will get an improvement.
