Decks, Patios, Porches and Docks - Cedar Deck Screwless/Nailless

I was well on my way to using either Timberdeck or Brite Composite decking for my deck, but lots of reading the internet has scared me back to Cedar. I feel like I am taking quite a chance for my two tier deck. Upper deck will come off the sliding door of the house and lead to the above ground pool..roughly 24'x24' (36" off ground) and cut around to match the pool's perimeter/edge. Lower deck will be built on those dec blocks and be 18'x24'.

Few questions for all the pros out here, if I may.
1) I really want to have no screws/nails showing on the top and after much research on hidden fasteners like tigerclaw, deckmaster which was going to cost me $1000 for fasteners...ouch... So, then I started researching tongue and groove 5/4"x6" cedar. If I can't find it I can always get it milled...but what are the cons of T&G Cedar for outside decks in climates of Western NewYork/Canada...snow/rain/high and low temperatures....should I drop this idea?

2) Guess the second question really is...am I running scared on the Composite for no reason, meaning the mildew/staining problems of years gone by have all now been corrected?

3) For a lower deck of that size, any negatives on using Dec-Blocks?

Appreciate any help...Jeff

My in-laws have composite on a deck on the north side of their lake home - no mildew or staining problems.

You can't use T&G for a deck - there has to be space between the boards to allow for precipitation to drop through or it will pool on the wood and accelerate the decay.