It's not too heavy, just awkward to lift/move with just one person. I made it so the front folds up, or you can use the doors on the front for access.
I'll be honest, when I first started my tank everyone told me not to use the glass covers. I didn't believe them and used them anyways as, like you said, it made for less evaporation. Unfortunately, it also limited my CO2 exchange at the surface so my pH levels were all over the place. Once I removed them and placed egg crate on the top, the pH levels were back to good levels.
I'm not telling you what to do, just sharing my experiences.