Base structure will indeed make a difference to speed and all new skis from the factory will usually have a universal structure for average conditions in average winter temps anywhere in the world. If the temps are significantly above or below average they won’t be as fast as they could be just like if have the wrong temp wax on for those temps.
All things being equal as far as structure, wax etc, the sintered base will be faster and more durable(as they are more dense) than an Extruded base. An Extruded base gets a little bit faster with wax(but never as fast as Sintered) but the unwaxed extruded base can be faster than some unwaxed sintered bases. Waxing and structure always makes a bigger difference with a sintered base and less with extruded bases, so the term “less/easier maintenance” is often used with Extruded bases as it will make less of a difference with them. Even if never waxed, they don’t get that much slower vs a sintered base that will get noticeably slower without wax.
Durasurf is the manufacturer of Sintered bases that ON3P, Moment and others use and they typically use the 4001 model. The number companies use in the model number is usually the density(roughly it’s hardness) although it could vary from company to company I’m sure. So a p-tex is 4500 denser than a p-Tex 2100. Most “race bases” are in the 4500 range and infuse graphite in the p-Tex which improves glide.
ON3P uses a dense base and it’s thicker than normal too, as is Moments(but not as thick as ON3P uses) so ON3P are kinda the champs of beefy and still fast bases. They use coloured bases rather than graphite infused black ones so they wouldn’t be as quite as fast as ones that are.
I’m a tuning fanatic with all my skis and there are definitely differences between the speed of bases but probably not as noticeable as people probably think if proper maintenance is done on the bases and edges. Waxing and making sure edges are smooth and burr/nick free makes a big difference.
All this being said, my 2017 ARV 86s had noticeably slower bases than my other skis that usually feature race bases. They didn’t take wax like a higher end base does and wax types didn’t seem to make much difference. Would like to have them back as I’ve got much improved edge tuning equipment now so it could have been edge issues causing some of the glide issues. So BEST CASE, I’d say S7 is a lower end Sintered base but wouldn’t be surprised if it’s actually a thick Extruded base.