See my experiences with a single side power meter here compared to when I bought the right sided Assioma pedal to compare:
I would also take with a grain of salt any previous readings on bikes with ‘dual side’ power that said you had no imbalance. When I compare my left right balance on my Quarq Dzero which is a very accurate power meter for total power, it tells me I am 51/49… As soon as I used power pedals with actual left right numbers, as opposed to ‘virtual’ left right numbers it showed I had a big imbalance and a single sided power meter for me always will elevate my power.
That said, if all you want is a power number to train to then there is nothing wrong with a single sided. Why don’t you just use the stages to control your trainer, and use it outside. That way you have consistent numbers?