Exposed gas blocks on Magpul's Carbine DVD?

[Sffred]

Hello my fellow AR enthusiasts!

Noticed on Magpul's carbine DVD part 2 that most of the participants in Costa's training class is running midlength's with exposed gas block's. Is this the new FAD? I know SPR's have exposed Gas block's passed the handguard but never seen a middy that way. I like it. Thinking about doin' one.
If you guys haven't seen it. Most have 12.5" barrels suppressed.

[dentron]

12.5" mid lengths huh?

[Leaveammoforme]

So you're wondering if an 'exposed' gas block is a fad? Most factory carbines gas blocks are 'exposed'. I'm confused. A little clarification please.