I wanted to make sure I understood the differences between the generations.  It looks like the Gen 1 is a little longer & the baffles are made of titanium instead of stainless steel?  Is there anything else I'm missing?  

Any time frame on when the Gen 2 might be back in stock?

The baffle technology of the gen 2 was the subject of its own patent application.  The shorter higher performing unit was the second version that replaced the first after about a year and a half.

I think the holdup is manufacturing booster housings. The production schedule is pretty packed.  Those are a high priority item to get that can back in stock.