What kind of VST is SWAM using for Windows?

VST, VST2 or 3, AAX?

And are there any benefits from running an AAX host rather than just a VST host?

@ProDigit here are the complete specifications for SWAM: https://support.audiomodeling.com/kb/faq.php?id=40

Note that Solo Brass products are different from Solo Woodwinds and Solo Strings, as Solo Brass is based on a new technology. Solo Woodwinds and Solo Strings will be ported to the new technology in a few months.

Summarizing:

• Solo Woodwinds and Solo Strings: VST2 and AAX on Windows; VST2, AAX and Audio Units on macOS
• Solo Brass: VST2, VST3, AAX, NKS and Standalone on Windows; VST2, VST3, AAX, Audio Units, NKS and Standalone on macOS

AAX is a proprietary technology by AVID and requires AVID applications, i.e. Pro Tools or Sibelius. There is no apparent "advantage" between AAX and VST, except for the availability on AVID products.

Best!