How bad is it?

Do you think it is common that you have to gate check your rollaboard wheeled carry on bag nearly all the time? In reality, if one more bag has to be fit into the bins, it is always possible. There is always enough slack to fit one more bag but not necessarily 10 more.

I believe you can expect to have a middle seat in the back third of the plane. There is only one last row so the chances of being in the last row middle seat are low.

Of course, it's possible to get certain credit cards to get earlier boarding.