I'm having trouble deciding whether to get a M or L plasma thermal jacket. I'm used to wearing size L but they're usually a little baggy on me and I've been told that I might need Medium. I am 5'6" and 155lbs, what do you think?How snug should a jacket be? For example, If I grab the jacket in the middle of the chest while it's zipped up and pull it away from me, how far out should I be able to pull it away?Also, if the bottom of the jacket ends almost 5 inches below my "rear end" is it too long? The large is that long and the medium is maybe 2 or 3 inches below.Is it ok for a jacket to get snug at the bottom when you crouch?Sorry for having so many questions, thanks for reading! Any good tips on how to decide?

Tech Specs:

Material:

[Shell] 40D HyVent Alpha (100% nylon) 

Insulation:

PrimaLoft 

Waterproof:

Yes 

Core Venting:

Underarm zips 

Seam Taped:

Yes, fully 

Powder Skirt:

No 

Hood:

Yes 

Pockets:

2 Front, 1 chest, 1 internal security 

Recommended Use:

Mountaineering, skiing, alpine climbing 

Manufacturer Warranty:

Lifetime 

Country of Origin:

China