Mountain Hardwear - Lamina Eco AF 15F

That's fairly extreme compared to what most people camp in though I camp in that and lower too! I actually pair the 15F Lamina with a 3 season down bag and come up close to that weight. it requires a fair bit of down for extreme temperatures and down's expensive. Your Lamina is synthetic and will still insulate while wet unlike down which is better for a beginner as soaking a down sleeping bag could potentially be lethal. Yeah the weight sucks and it's a bit overkill. People typically travel shorter distances in smaller time frames which helps negate the weight. You can also use a sled as many people do. The reality is you're going to feel the weight if you are carrying winter gear. Atmosphere does tend to hire staff with zero outdoor experience FYI. I'm kind of surprised they even offered an opinion.

I have the marmot sleeping bag and the lamina sleeping bag you reference here. While I was in the military I was taught ounces are pounds. That said, for your purposes these two sleeping bags are fairly negligible either way for your purposes. I like how small the marmot packs down, but I use the lamina more in all sorts of weather. It’s more comfortable to sleep in. I would say you are fine with sticking with the lamina until you decide just how much you like hiking and camping and then spend a little more time to build out your kit list and budget then go from there.

Welcome! I love the lamina, and it’s pretty versatile in my opinion. Is it “top of the line” no, is it comfortable yep!!!

Mountain Hardware has a couple bags that are compatible, my wife and I use them. They are a little bulkier, but affordable. You could also look at something like the Zenbivy Double bed.

I have the Mountain Hardwear and love it. My kid has a North Face Inferno and loves it… and I worry less about water damage. I trust OutdoorGearLab.com for reviews. 

It's really a personal choice. I would suggest you try the MH sleeping bag. It's a free way to test a type of sleeping bag. Worst case, you buy another one later. I personally use down sleeping bags because they are lighter and compress better. But they are more expensive and take a lot longer to dry if it gets wet.