Controling zwift with external power meter

I have just had a couple of rides with zwift and wandering if I am using my power2max external power meter on my bike rather than the wahoo kickr to control zwift will I be able to feel the climbs or do I need to use the wahoo kickr’s own power meter?

By feel the climbs do you mean the gradient/resistance change? If so, your smart trainer is what’ll cause you to feel the gradient change due to it being a controllable trainer. Power meter’s just read your wattage output.

As long as you have paired the smart trainer within the ‘controllable trainer’ field then Zwift will let your trainer know what resistance is required.
Your power meter, again if paired correctly, will tell Zwift what output you are currently doing.

For me, using a power meter on the bike is best. You can then measure power on Zwift and on the road using the same device which provides accurate cross referencing.

My experience with using the crank power meter in conjunction with the controllable trainer is that there is a significantly more noticeable overshooting when a high resistance kicks in and a lag of some seconds, compared to using the trainer build-in power reporting.
It depends on what you want to focus on. Until I moved on to the Elite Direto trainer - which accuracy wise is spot on - I had a Tacx Vortex that reported at least 30 Watts higher that what I was actually doing. That was the reason for setting Zwift up to read the Power from my 4iiii and the Vortex as the controllable Trainer.

Cheers, Matz