In reply to Gabe Oliver:
Own a Shield and agree very much with the above comments; it is perfect in both design and performance during Winter but find that it may lack a touch of breathability in Summer conditions, especially during higher output aerobic activities.
Guess your decision is based on what you will be using the jacket for most. Any compromise, by its nature, results in a jacket not ideal for either season, since the conditions faced can be the polar opposite...
Love the Shield in Winter though...