I just found them good for consistency in accuracy/performance, so used them on certain builds , but never did any side by side comparisons when fitted to the same blaster to gauge any differences between the two materials.
Quality polished Alloys were used for the bulk of the upgrade builds and were putting out decent performance at a good price, so wasn’t any need to upgrade to the more expensive SS barrels unless specifically requested.
The stainless barrels are more rigid, hence less vibrational deformation. ( it’s called a gel for a reason and anything that bounces will carry a vibrational resonance (reaction) long after initial flight (action) Corrosion is another factor in the choice, as alloy will need more maintenance due to the makeup of the gel with moisture in reaction with alloys. Thin strip of soft rag in some doubled up mig wire then spin in a vice with the cordless to make a pull rod and use wd40 silicone spray as the protectant, works well. Hydrocarbons have evaporated off long before you use the blaster again.
Highly polished does not necessarily mean less friction as we are delving into hydrodynamics with wet gels,
Excellent advice!
The “friction” part that I encountered were from the generic brand online drop shipper sellers who advertised cool looking replicas of the higher quality manufacturers…… but their internal finishing resembles 40 grit sandpaper! 
That’s definitely where the “friction” issues come into play, no matter how well lubricated the gels are with water content 
As has been commented, it all comes down to how the internal finishing holds up to the rigours of use and degradation.
Stainless will always obviously hold up as the best material, quality Alloy second and Brass can be very difficult to keep clean/polished without the right equipment.
Certainly get what you pay for at the end of the day, and barrel cleaning/maintenance should be mentioned more in the context of keeping your Gelblasters performing to their potential.
I lost count of the amount of people having issues with losing performance/accuracy, yet when I stripped them down, probably 80% of it was simply due to dirty barrels that were easily fixed with a good clean and polish 
EDIT Pro tip…. old school plastic coated washing line wire with a strip of cloth and a high quality “Hot Rod Grade” fine alloy polish on the end of a drill works wonders! 
… and then you brew a new batch of your favourite gels and nothing shoots straight anymore
Flashbacks to the X-Force Black Label’s and my long awaited testing of the AUSGEL Ultra Elites!
black packet AKAs - never happened before
Never had the opportunity to use any modern AKA’s, only early rainbow coloured different offerings before the invention of “ultra hard” gels.
Truth is that there’s actually only a couple of factories that manufacture gels for all of the different repackaged/branded suppliers on the market.
If one “brand” had QC issues……. that followed into all of the other rebranded Gels sold through other retailers
No I didn’t tbh. I have both SS and alloy 7.3mm ID. The only thing with the alloy is more prone to corrosion from the water from the balls if left stored wet. I just punch it with a cleaning rod and cloth with a bit of anti corrosion whatevers your flavour seems fine
The good Ausgel alloy anodized outer inside polished barrels are really good. Don’t hesitate to get one.
But the CHGBB SS barrels came out a couple years before Ausgel started making good alloy barrels, so there was that.