Yeah, I have the Iwata HP-CS with both the 0.5 and 0.35 needle/nozzle sets. It's a good brush and I like it, though sometimes (if I don't get it cleaned out as well as I should) I'll pick it up to discover the trigger has become stiff/stuck. But, a thorough cleaning resolves it.
Also separately purchased the crown cap for closer detail work, but not really sure it does much for you.
In the meantime, every place I looked into for the HS brush (HS# 126594) wanted $320 for it. But I found it at air-craft.net in the UK for €166.66! So (in theory) even after any applicable customs and the exchange rate, I should come out ahead.
I'll follow up once I've got it in-hand!
Between the two brushes, I'll now have the option of 0.2mm, 0.35mm, 0.4mm and 0.5mm.