The low flows are badly named as the flow is actually the same in all pistons(its the amount of fluid displaced by the damper rod) in a large port design like the gold valve the velocity of the fluid will be low.In a small port design the velocity is high.So a low flow is better described as high velocity.Saying all that the people who use them are pro-action(had some dubious quality problems in the old days) and mx-tech(forum sponsor) and gp racing.
Pro action is the available in the UK.
The low flows i do believe give a slightly better small bump action.The difference form a really good set up on a std piston to a low flow is small but then so are most things as you push the limits.One thing is for certain-the showas are the best suspension available-many works forks are just straight copies of yours.
MX tech is available by MXW in rugby
Gp racing is US based.