You seem like a nice person and I'm feeling generous after the combustible stair and intermediate handrail thread earlier today. Plus this isn't something you can just look up in the building code. So here are a couple of bullet points to help you out:

• This isn't butt glazing, this is structural silicone glazing (SSG). There's a difference.
• Pro-tip 1: Don't call these a 'cap-less' system, call them a SSG system. The cap (snap-on cover, snap-on trim, beauty cap, etc.) snaps on to the pressure plate in a non-SSG system. It is cosmetic to cover the fasteners that are used to fasten the pressure plate back to the mullion. Here's a diagram with some labels.
• SSG systems will give you the "no outer cap" look because they don't use a pressure plate to mechanically retain the glazing. Instead the structural silicone sealant bonds the glass to the mullion.
• Pro-tip 2: Don't call the visible portion of the sealant between two panes of glass structural silicone, or butt-glazing sealant or something else like that. Call it the weather seal (or weatherseal sealant) instead. Can you guess what its purpose is? Here's a diagram with some labels.
• Operable windows like this are referred to as venting windows ... not exactly sure why. There's probably a reason, but I haven't learned it. 

Armed with the information above, you should be able to find a window and glazing system that will give you the look you want. If you can't ... Kawneer's Glassvent is one that comes to mind. YKK AP's YES SSG Vent is another. US Aluminum/CRL has a couple as well (7500 Series, maybe?). Just make sure they'll work in a SSG framing system.

What is the life expectancy of that silicone weather seal? That seams like a fairly important seal that would easily get overlooked by most building maintenance people.