Thinking about switchin to them .  Looks like they come with a 100 grain outsert, and I'm shooting 200 grain VPA 3 blades already on a .400 carbon.

The extra arrow weight doesn't bother me but wondering if the 400 will be too limber with the extra outsert weight? The small diameter will help I guess...

Bow is 47 @ 28 , fairly quick bow and I draw 28" .  Beman Centershot 400s cut to  30" with 200 up front that I'm using now fly great.

Any hints and pointers appreceiated ...

Those Centershots are 9.6gpi.  I know because I use them as well.  I would go with the BE Vintage.  Pretty close in weight and diameter.  6.5mm vs 6.

I know that's not what you asked but an outsert really takes away any penetration gain of a skinny arrow and can be tough pulling on 3D.  Not a fan.

I've used the instincts.  Keep in mind that this is a much skinnier arrow than your center shot, so all things being equal you will most likely need a stiffer spine.  And if you want to stick with that 200 grain head plus the 100 grain insert, stiffer still.
I can't give you much data on how they perform on game other than to say that I shot a large doe with a 500 spine instinct w 175 Zwickey for @535 grains.  The arrow was found 30 yds down the trail, having made it out the other side.  Bow was a 40# PCHX.  The insert is about as wide as the ferrule-- of the broadhead so it allows the skinnier shaft a wider hole to follow, possibly enhancing penetration.

Thanks guys , I said that wrong on diameter . It will make it more weak !

Sometimes I just want more arrows ! LOL

I have killed a lot of critters with them and still use them, but would not necessarily recommend them.

The stock outsert makes for a very weak spot behind the insert, and I have had multiple breaks on angled shots.  Also not much surface area for glue ,so you can lose tips on targets, especially if shooting broadheads into certain materials.  I switched to using the ethics archery insert/outsert and it works better, but a bunch more money and the inserts can still bend on an angled hit.  Eventually I will either use day six if I want a skinny shaft or just use the vintage shafts, which work well.

Kenny I just finished building and tuning some .400 spine instincts for my 44lb@ 28 bear SK.  Finished out with 200 gr head and 30.75".  I had been shooting .500 spine standard diameter carbon and had hoped to have a longer arrow for reduced point on distance.  The smaller diameter instincts moved me closer to center shot and it was basically a wash as these arrows are only 3/4 inch longer than my .500 spine at the same point and insert weight.  However, they finished out at 610 grains and shoot really well which is what I was going for in a hunting arrow. 

I like them a lot and think they're a great value - I'm shooting 29.5" 400s with a 150 gr head from a 50# Widow PSA. No trouble with targets or penetration, in fact the reason I like them so much is because of how much more they penetrate compared to a standard diameter arrow. It seems to hold true on game as well as I got a complete pass through on a quartering away buck last year with a 3 blade VPA.

Thanks guys! Great info!!

You could also use the Valkyrie system with them.. They sell center pin broadhead adapter so you could use them with any glue on head..

All those different components and sizes. Must be why I stick with wood!

I don't shoot them yet, but here is a good review:  https://www.youtube.com/watch?v=tiPaGpwi0cI

Thanks again guys. I'll prob stay with what I'm shootin since I have several and am tuned with them.