Hi,

I cannot give advice on glue but I'd think any effect similar a knurled finish would be good,

I use to make stainless nut inserts for epoxy valves and we always knurled the outside.

you need a good structural bond, hysol 9394 or 9396 are good and ive used 3m DP190 for bonding bike frames together.
the key is abrading both bonding surfaces and cleaning with acetone, if you need to maintain a glue thickness you can add micro balloons of the correct size to the bond material prioir to applying it.

I use Araldite 2015 for metal to composite bonding. It's amazing stuff, I had the pleasure of going to a local composite bike frame 'factory' and watched them performing a load test on one of their ali/carbon bonds with Araldite 2015. The pre-preg carbon gave out before the bond, the bond actually never failed. 

Thanks for the advice. 

I have done extensive tests on bonding both Aluminium, stainless steel and Titanium to (and into) CF Epoxy based laminates and parts..

I did not get any improvement when using etching on any of the metals.   A good thorough  "scoring" of the surfaces with abrasives as coarse as 80 grit seems the most effective.

The "cyano-acrylate" based "superglues" such as "Vuduglu" Black and the Araldite Epoxy glues give bonds so strong that usually the laminates fail before the bonds. Even normal laminating Epoxy with high density filler and Carbon fibre filler gives a very strong bond.
In the case of bonding in tubing ends, most of the mechanical load will be in directions where the tubing itself will "carry" most of the load.. (depending on the intended use of the tubes)

I recommend reinforcing the outside of the tubing by winding on some kevlar tow with laminating epoxy, over the part where the metal is bonded inside the tube.

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