I've seen some of the deck "rejuvenation" services where they
guarantee the deck for 3 up to even 25 years. Aside from having
industrial sprayers to clean the wood (3-4000 PSI), what do they do
that's different from what you'd do yourself with a sprayer and deck
sealer?

Since super high pressure will tear up your deck, so the biggest
difference is that their equipment has to be used at a greater
distance and covers more area faster, I figure the difference is
either that they're exaggerating about the durability of their
coating, or the coatings are really, really great. Maybe some sort of
plastic sealer?

The prices of these services (in my case, at least) turns out to be
about 2-3 times the cost of my tearing up all the old planks and
replacing the walking surface of the deck completely But then,
(according to them, at least), I'd have to seal that new deck again
anyway in about three years.

Is there any value to these services outside of appealing to folks who
just don't want to bother with the hassle of replacing planks? Or are
they really going to preserve a deck for 10-20 years -- i. e., longer
than the life of a new surface?

And for that matter, since, in my case, for example, the cost of the
treatment is about the same as pulling up the old surface and
replacing it with a manufactured/synthetic material, is it better to
just do that -- go to some sort of composite/plastic for the walking
surfaces?

Thx!

Mark