How much smaller (and lighter) do down quilts tend to be when packed than equally-rated synthetics?

and

How much more difficult (read: annoying) was the building of the down quilt? Was it worth it (aside from the accomplishment aspect)?

I'm gathering the data I need to make a TQ/UQ setup capable of keeping me toasty down to 20F, and I'm trying to decide which way I want to go. Synthetics seem to have the edge in ease of manufacture and cost, but I know their lower loft-values render them heavier and bulkier. Synthetics are more water-resiliient, but good down is ultimately more durable. Down can shift around leading to poorer insulated spots, but synthetic sheets are immobile.

Does it really just come down to personal preference and how much of gram weenie you are? Am I just being shortsighted by considering a full-synthetic quilt for my first DIY insulation project? Do you gain the best of both or the worst of both with a hybrid/mix? Is there a preferred synthetic insulation material for a "high-loft" application like a 20F quilt? Can this get any more confusing?

TCB