Unless I have overlooked something, your initial post does not indicate any issues with the CTEK, thus I would advise against hastily replacing it.
Nonetheless, the CS ONE is an excellent piece of equipment. The CS FREE can be utilised for in situ charging, similar to the MXS 5.0 and the ONE, but it also possesses the capability to jump-start vehicles without requiring access to a 240v power connection, so offering an additional practical function.
It is important to note that the CS FREE employs a somewhat big plug, which may prevent the cover of a waterproof outdoor socket from fitting and sealing properly when connected. It is worth considering.