I think it depends on the price point of your home. If its a starter home on the smaller size, then do the big box stores. They are probably the least expensive and you could paint them yourself. If you are in an estate home...more expensive home in your area, then go to a door distributor to get a solid door instead of the hollow doors from a big box store.

Marvin Ultimate is a wood frame rather than fiberglass. Its more expensive than Integrity overall and there are mixed signals about the longevity of cased wood windows versus fiberglass or vinyl. Marvin is as a whole is very highly regarded tho and they are the producer of both lines. The Ultimates have more customization options over fiberglass Integrity. There is just some things you can't easily do with fiberglass as compared to wood. For example, our home is going to have some gothic arch top windows. I couldn't get them in Integrity and had to again go Ultimate for those particular windows. And believe me, they aren't cheap (probably due to the custom gothic radius). But the outer colors coordinate between Ultimate and Integrity so it will hopefully be a flawless mix. Windows aren't installed just yet or I'd post pics. I wouldn't believe white painted interior on the wood ultrex would be any less clean looking than all ultrex assuming whoever is painting knows what they are doing. I'd definitely track down a showroom and compare the two lines side by side. With the Wood ultrex its just a more classic looking window profile I think. The all ultrex is quite plain and almost, I dunno, cheap looking in comparison. Its definitely the more durable option tho, no paint to scratch (although the fiberglass can be painted) or wood surface to ding... Its a judgement call for you really. The Ultimate sliders come in 4 panel yes, in 10, 12 and 16 feet wide it looks like straight out of the catalogue. OXXO configuration so the 2 middle sections open to form one opening and net clear openings here listed in my catalogue lead me to believe if both are open, there is no obstruction in the center. The 12' wide one has a net clear opening value of 57 7/16" (or 59 for the non french door) The ultimate sliders have 2 versions..basic patio door and french door. The french door version has wider rails framing the glass, to mimic the look of a french door. The basic version has more glass area and thinner rails so if you go that route make sure you choose the model you prefer To throw more choices your way they do also have these in 3 panel like the integrity but in greater widths. I see here a 12' three panel as well if you just want one active slider but a little wider than the 3foot operator of the 9 wide integrity..lol What you should be looking for to find out how drafty these types of doors are in order to compare them to each other is air infiltration values. Unfortunately with Marvin these can be a bit of a hassle to come by but you could take numbers from a similar manufacturers slider and compare it to your lanai or bifold doors to maybe get a rough idea.

It's an OXXO USFD that you are looking at. Millworkman is correct that the debris in the track is the key element in causing the door to operate roughly. Installation is also key. A plumb, level, and square door will operate like a dream. The Lift and Slide is meant for a new construction application and has a 7/32" tolerance on the sill. Not much can collect there, but you are also not rated for water infiltration. 9 pounds per square foot is the approx. weight on the panels. It all depends on what you are going for in regards to design.

Good side is that it means my window guy is legit and looking out for me, bad side is that I now have to spend $13K (:eek:) to get the look I wanted with this room. He was pretty clear that part of it is they will need to beef up the structure to support the doors.