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.

I just remembered that my linen closet has the same type of sliding doors. Looking at those doors there is no big play at the bottom where the door fits into the guide. These must be adjustable and I just am not able to see from this angle. I don't know what word to use, but the area for each door to fit into is fine on the linen closet doors. The bedroom doors are another thing. One door fits nicely in the alloted space in the guide. But the other guide looks to be spaced way to wide. So that is why the door is able to jostle around. How hard is to remove the screw holding it into the concrete and then screwing it down through the carpet and concrete in the new adjusted position. Do you need to do anything special to get it to screw into the concrete? Can I use the same screw? Sorry for being so home repair challenged.

Some of the posted pics are not the most current (punch list stuff since completed and we painted the ajoining rooms) but they are close to the finished product. I'll post more current pics later. Although our GC handled cooridnation with Fieldstone, they seemed to be was great to work with - there were a couple of cabinet panels that needed to be changed out for size, we needed a replacement pullout, other odds and ends. Fieldstone shipped replacements no issues. Overall we're very pleased with cabinetry quality, fit and finish. Our GC (Tri-County Development in South Jersey) was/is outstanding. Could not be more pleased with thier quality, responsiveness, subs, workmanship. COVID and Supply Chain issues slowed us down a bit but overall, we are extremely happy with the project.

That really shouldn't matter, a fold is a fold if it is the right kind of hardware. But here is another option. Johnson Hardware 200RD Multi-Fold Door Hardware | Jhusa.net | Sliding | Folding | Pocket Door Hardware