LPP ( pullover ) - really warm, bulky, bulletproof, kinda heavy but great to throw on over all your layers for around camp or glassing.
Grumman - pretty warm ( good early season jacket for BC ) super light, super fragile.
I might get strung up for this but I honestly didn’t find the LPP to be anywhere near as warm as a typical down puffy. By typical I mean 800 fill power and somewhere in the ballpark of 4-5 oz of fill weight. I sent mine down the road.
I just finished a backcountry trip in Colorado and brought the SG Grumman (first trip with it). Its ultra lightweight and surprisingly warm for the weight. I was also surprised at how well it blocked the wind since it isn't made for that. Definitely would recommend it for a backpack trip. The LPP will probably be a bit more durable than the Grumman, but it won't be nearly as light or pack down nearly as small.
Buy the LPP if you are going to be wearing a jacket for most of the day in any terrain that may touch the jacket. Buy the SG if you may want to put on a layer for warmth but are more concerned about weight and compressed size.