No. Wool is the new wool.

Fleece is what the manufacturers of synthetic pile do to their customers!

Nothing performs as well as wool in as wide a range of situations and climates.

If you haven't done so, I suggest you check out such companies as Ibex, Smartwool, Filson, King of the Mountain, etc. to get an idea of what's being done with wool today.

Personally, I have resolved to eliminate plastics from my outdoor gear wherever possible. I've even thought of starting a retail business to provide all-natural travel, camping, and survival gear. The only areas I have found so far where natural materials are at a significant disadvantage is in sleeping, shelter, and climbing gear. Everywhere I can, I subsitute wood, metal, leather, or natural fibers for plastic. While many of my substitutes are heavier than equivalent plastic items, the additional utility of a stronger, more repairable item is worth the trade-off...not to mention the lessened environmental impact.