I understand that. I was very careful when getting the Rage War trilogy, I made sure they're all paperbacks and the same size (as some are smaller, I think it's the US editions which are smaller in size despite being paperbacks.)
So anything part of a series, I prefer it to be a matching set. But if it's a standalone book of that franchise, then I can tolerate it. But like you said, hardbacks can be huge and take up more space than paperbacks.
