I’ve carried a haglofs l.i.m. on every trip for the last year, and I think its a really useful layer. I use mine as a second baselayer that can also double as a mid. I also love sleeping in mine because of the close fit of the scuba hood. It goes well under a wind and a rain shell.
The L.I.M. excels in wicking/breathability, and it makes for a great baselayer in the colder 3 seasons. The L.I.M. is generally enough hiking warmth for me, particularly with a windshirt layered over. Sometimes on a long exposed ridge, I’ll throw a puffy over all that while I’m moving.
I bet the chameece or 100 weight fleece would be a good mid layer to wear for cold rain, because of a little extra warmth/loft. I’ve spent many hours hiking in the rain in my L.I.M, but it can feel a little damp if the weather is consistently cold and wet. It does work great as rainy day baselayer though, since the grid keeps much fabric off your skin. A 100 weight fleece could be better as a mid, but fortunately, in the rockies, consistant rain is not the norm. Hard to make a recommendation one way or the other since personal warmth will depend on a lot of factors from metabolism to pack weight. Regardless the LIM is a really effective/versatile piece to own. Way overpriced at retail, but you can occasionally find one on sale for less than $100.