High flow nozzles  

RE: High flow nozzles

High flow nozzles split the molten plastic into separate channels and then recombine at the nozzle tip. They allow you to essentially print faster than a standard nozzle. So for example, a print with a regular nozzle might take 4 hrs but with a high flow maybe 2.5 hrs. Really depends though on the type of filament. A disadvantage of a high flow nozzle is if it clogs it can be difficult to unclog. Also, certain types of filaments have to be printed at slower flow rates so there won't be an advantage to using a HF nozzle in that case. I use both HF and regular depending on what I'm printing and with what material. 

RE:

You can run a simple experiment: slice the same object with HF and regular printer setups, then compare print times.

If the difference is small and you want to dig further, change the display mode in the slicer to "actual volumetric flow rate". More often than not, the printer is slowing down for other reasons than the flow rate limit (e.g. to improve layer adhesion) but you're free to change that if speed is most important e.g. as "DRAFT" mode.

One disadvantage of HF nozzles is that their internal structure is easily damaged by the steel needles that are being sold along with the printer. Once damaged, they misbehave and cause quite a lot of grief (BTW I've never found use for those needles, "cold pull" should be used to clean without risk of damage)

Another downside is the increased internal volume - cleaning them out when changing material is more difficult (purge volume). And mixing materials in the critical first layer of a print is usually a bad thing so a HF nozzle may require more attention in daily use. 

My own pick, usually 0.4 mm regular because of MMU (purge volume). And I don't see myself swapping it for a single-color print unless maybe for a some massive object (and in that case, 0.6 mm might be preferable).

I don't use them, many experienced users don't ... but inexperienced users and speed junkies clamor for them so manufacturers are more or less forced to offer them or seem outdated.  

Nozzle flow is rarely a limiting factor - only on long, straight runs of deposition does the tool head reach speeds where the extra flow makes a difference, for most small to medium sized prints the difference is negligible and it doesn't justify the downside - the slightly increased tendency to clog.

It might be worthwhile if you intend to print a lot of relatively large parts.

Cheerio,