Can anyone tell me what the difference is between the Physio/Comfort Enhanced vs the Physio W3+/Comfort W2+? I've read the Enhanced versions are 100% backside freeform, but I can't find anything about the W2+/W3+ in comparison beside the marketing fluff about WAVE technology and nothing with a direct comparison or why I would use one over the other. Are the W2+/W3+ backside freeform also? Thanks.