.....teak is very hot on your bare feet and splinters are a sure thing, teak never looks good unless it is varnished and requires several more hours of maintenance each year. and it is not will it leak it is going to leak because putting a million screws through a fiberglass deck is just a very bad idea.
Seems you might be describing these attributes from rumor. Yes, teak can get hot, but not instantly. If it's wet, it's never hot and yet still holds one's foot well. Better than many non-skid patterns. There are aggressive non-skid patterns or textures that always hold well. However, by definition, they are aggressive on your foot. Teak does have it's advantages.
No one ever varnishes a teak deck. That wouldn't make any sense, it would get slippery and lose all the properties one is looking for. Varnish is for trim, handholds and tables. Some will oil the decks, but that attracts dirt. Others will seal them with something like Semco, but it looks terrible, IMO.
As for routine maintenance, I let mine weather grey. A scrub with salt water weekly is a good idea. TDS makes a new one part Eco-cleaner that is amazing. It's bio-degradeable and you practically just lay it on, scrub lightly with a scotchbrite and rinse off. Done.
Many decks are glued down, but there are still some screw holes from the bracing that holds it in place, while waiting for the glue to cure. These are supposed to be filled. Often, they are not. In my case, I keep finding the actual screws, buried under the caulking.
Teak decks would not be a great idea, if you were in tropical climates 12 months out of the year. They would wear much more quickly and replacement is breathtakingly expensive.