Flashy Shot-1 Rapid-5
Stealth Shot-4 Unlimited-5
Snap shot-5
I would suggest 4 Stealth merits over 4/5 Flashy shot. Flashy shot is designed for people who can't reach the highest damage tier on monsters. Songs + Dia + Def. down (angon/acid bolts) allow rngs to reach this cap faster making stealth shot a better choice. The only time you benefit from Flashy Shot is if you don’t have the proper buffs but that shouldn't happen in most cases. The merit combo I use benefits my setup better because all the fights I am on ranger last about 30-40 seconds. I guess the point of the discussion here is if you like to die or not. Flashy shot recast timer is nice but only useful if you don't have the proper support.
My LS gives me the proper support so Flashy Shot doesn't make a difference because I am always at the highest damage tier on ranger. The only monster that I can think of that flashy shot recast might be decent on is JoL. My LS kills in JoL in 22-28 mins., so I rather use Stealth 4 to 5 (at -40 enmity) times instead of using Flashy Shot twice.
P.S. With x2 minuets, Dia II/III, Good food (rabbit pies/red curry), and Def. down (this is not needed but it helps) you should have no problem reaching the top tier on HNMs provided you have the proper gear. Kirin,DL, and Br2 included...
Though I don't disagree with you that Stealth Shot is a good choice to merit, you cannot reach the highest damage tier on most mobs higher level than you. Level correction is one of the most pertinent part of damage calculation which is what Flashy Shot circumvents.
You don't really need Stealth Shot either if you have Coronach... granted that's a big if.
Cookie cutter setups don't fit all rangers.
You can have 999 rng attack, and flashy shot will still raise your damage. Level correction comes after calculating your pdif. Almost anything thats worth killing is higher level than you are, so it will always be extra damage.
For many cases I have seen on D Lord zerg, Angon, Dia III, double SV Minuet + Berserk + Cheap coeurl sub is already enough to cap your ranged pDIF. If you don't use gorget for WS, you'll most likely can find your Slugshot divisible by 15 (high chance ranged pDIF is capped) and barrage number is divisible by 3.