Down or Synthetic Jackets

[Moondog55]

Applicable to every type of clothing system, even wool and cotton systems, but it gets forgotten to often when I buy new gear. I have a superb DBStuff P'Tec 300 jacket that won't fit with any of the new gear I have

[Joomy]

I'm no expert on this but I have read that the synthetic layer (be it jacket or sleeping bag)should be the outer layer if you wear/sleep in a down layer as well. I believe this is because the moisture moves to the outermost layer eventually and it's better off in the synthetic over the down for obvious reasons.
I have no first hand experience with this though in actual effect. I have layered a down vest under a synthetic jacket though and found it worked well if the sizing is right. My primaloft/coreloft clothing is all sized to fit over my UL down vest for this reason.

I've highlighted in bold what I consider the most important part of your post Forest, no matter what system you decide on this is I believe the most important part; everything has to have the ability to work together.

But synthetics produce much more resilient loft and so it takes greater compression force to reduce their thermal value compared with down. Therefore I would argue that having down on the inside is always going to result in more loss of warmth from compression than having synthetic on the inside. Plus synthetics don't need to loft as much in the first place to provide their warmth, which means a less bulky garment, which means your outer garment need not be so over-sized, which equates to a lighter outer garment. Whether this is counter-acted by other effects is the question such as moisture build-up within the down layer is the question.

[wayno]

i'd argue you should start another thread about combining different jacket types i think its gone on too long and has diverted from what the OP wanted to know

[Joomy]

i'd argue you should start another thread about combining different jacket types i think its gone on too long and has diverted from what the OP wanted to know

This is the second time you've posted about what you think is undesirable off topic drift in this thread. If a mod wants to separate this into two threads then fine but I think this is all useful information, broadly in line with the OP's original question, which has long since been answered anyway. To start a new thread without moving the earlier posts across would be pointless.
As GPSGuided already commented:
"On the Internet and in real life, thread drift is but a norm. In any case, I think the original question has pretty much been answered and we are but digging up more angles of consideration in the down vs synthetic debate. A most reasonable evolution in an informed decision process."

[Moondog55]

I think I already said "Buy both" so I don't think the follow on discussion is OT at all.
It is certainly giving me something to think about with my next purchase. Thread do tend to develop a life of their own but all posts so far have been relevant to the OPs question