We went to one of those home shows this past weekend. It seems like every vendor their with the exception of Gilkey, Window World and Anderson have Alside windows and doors as one of the lines that they carry.
Window World uses them too.
I am assuming you went to the Homer Glen show? I have heard from a couple of people that they didn't have much variety of window offerings at the show. That is pretty different. The Tinley Park show a couple weeks earlier had about 50 window companies.
I used to install for Alside as a factory installer a long time ago. They had a service where they would provide professional installation to the siding contractors who didn't feel comfortable installing windows.
Nothing much has changed in their windows in the last 20 years, but I am not sure about the doors on whether they have updated them or not. From the website description they sound the same. Back then I didn't like them. They were real short compared to others and had a wood substructure in the jambs that I felt was a rotting problem waiting to happen.
Most vinyl window companies have a vinyl patio door so there are many to choose from. I would pick one with a composite type sill that doesn't stick up too high. and make sure there is real good reinforcement in the sashes. Products like Sunrise for example have pultruded fiberglass filled with foam in the sashes. Others may use steel or aluminum. The main thing is that it is sturdy. Many vinyl doors you can grab the sash and bow it in and out a couple inches....not good. Good luck to you.