Yes. Soft, absorbent, breathable merino wool is better than cotton or synthetics on hot days (and cold ones too). Wool pulls the perspiration from your skin, then passes it out into the air or outer layers, so you stay cool, dry and chafe-less.
I prefer this boxer-brief style (now the secret's out!) to either boxers or briefs- it gives the support of briefs, while protecting my thighs from chafing.
Machine washable, but I suggest Eucalan as a detergent.