very few pellet grills go down bellow 180F reliably... Even fewer actually have a temperature setting for anything below 180F I think GMG is probably the most affordable that does have a temperature setting down to 150F , a bit more expensive, but the only other I can think of that advertised being able to be set down to 160F are the Blazn' Grillworks grills.
But then some grills can actually run bellow their lowest set temperature too. Not sure exactly how low the Stampede can go and/or how it's "LOW" setting actually works. I know on a 80F day, I can't get mine to run much bellow 180F, I don't know what will happen in the fall and/or winter when ambient temperatures drop... that remains to be seen I guess.
If 'smoking' things like sausage and hot dogs is key to what you want to be able to do with a pellet grill, I would suggest you need to keep looking at other grills, and be very specific about your need/desire to run down well bellow 180F.
I manage to do this on my PG500 in late fall and winter... but even then, it can be tricky getting down to 150F or lower in a consistent manner, ambient conditions become a significant factor. The only GMG grill I own is the Davy Crockett... I'm pretty confident that I can get it to run at 150F all day long in cooler months, but it's so small that there's not much I would do on it at that temperature... I have considered just piping the smoke stack of my Davy Crockett into a box that I could 'cold' smoke in, to me that is the most likely way I would deal with it...
Anyway, good luck... I really don't think the Stampede would be your best choice for that kind of thing. A Bull with 'cold smoke' box attached might do what you want, but when you go to that , your at about $1430, which is a lot of coin.