I have Hehr frameless windows on an eleven year old trailer. I like the look and deal with the small openings by using the fan. Leaving them open in the rain is a nice feature especially in the Northwest. I had one leak due to a misalignment of a seal; some foam tape fixed that. One of the opener mechanisms came unglued from the glass. Gorilla glue made it good as new.
I use Meguires water spot remover to remove the spots on my windows with an electric buffer. Frameless windows makes the job a breeze as you can buff to the very edge of the glass. If I was ever again in the market, I wouldn't hesitate to get frameless windows.