Classic trainer on hills

I am currently using a Tacx Booster with speed sensor, cadence sensor and HRM and find during races I can stay with the pack on flats and downhills but as soon as the hills get to 4% and above I get left for dead by the pack even if I change to the 11T cog at the back. I know the trainer is limited to 400W max and being just over 70Kg I am limited to 5.8w/Kg I notice riders on smart trainers putting out upwards of 8 &9 w/Kg on hills, is this the reason I am getting smoked?
The reason for asking is I am about to invest in a smart trainer so would I notice the difference on the hills and hopefully be able to stay with the pack more easily?

It won’t be easy but you wont be limited to 400w. So yes the smart trainer will allow you to put down more power and you will be able to climb faster if you can produce that power.

Gerrie, Is the pick up from the smart trainer much quicker than from the classic as I seem to notice I am putting down a lot of power and it takes a few seconds before the avatar reacts to this?

It will be the same for any trainer. As the power on screen increase the speed of the avatar will increase. There is a delay due to the mass of the avatar so you need to accelerate the avatar.

thanks for the advice it is greatly appreciated.