choosing new canopy

I am 90 kg ,  have about 400 jump and my current canopy is a Sabre2 190sq  with 80 jump with . 
I intend to change my canopy to Saffire3 . 
Which size of this canopy do you recommend and how many size am i allowed to downsize ? ( 159 or 169 sq )?
Also what about reserve canopy ? should it be larger ? if so ,how many size ?

 

Brian Germain has a good article on down sizing. And a chart to go along with it. 
It's a sticky in the 'Canopy Control' forum.

BillVon has a very good article on downsizing in the 'safety' articles.
He includes a good checklist of skills you should be able to demonstrate on your current canopy before downsizing.

Strongly suggested to only go down one size at a time. 

It's suggested that the reserve be approximately the same size as the main. Not everyone follows that advice. 

Some folks like as large a reserve as they can fit in their container. Some companies make rigs that hold tiny mains and reasonable sized reserves. 
One of the jokes that applies here is:
I've never heard anyone look up at their reserve when they needed it and complain that it was too big.