Would he possibly be more into a more structured carrier? DH LOVES the Ergo. I like the look of wraps, and I doubt DH would have a problem using one, but I think the structured carriers might look more "manly"? And even though he likes carrying the kiddos, the woven wraps have a learning curve as far as putting them on. I think men tend to like more of the "buckle and go," which the structured carriers provide. DH will use our Moby wrap, but I always have to help him wrap it...
That's DH at the coast this weekend, carrying DS in the Ergo. DS is 2 and half. We bought the Ergo new, and at the time I was thinking "why am I buying something that's over $100?" 2 years later, it was worth EVERY FREAKING PENNY. And DH agrees!
Or maybe just show him a picture of Tamera's DH... He is a pretty darn manly dude in those photos!
FWIW, the Bjorn is bearly comfortable at 9 pounds. Put a 15 pound baby in that sucker and try to walk a few miles, and I guarantee that your shoulders will be screaming the next day. Maybe try showing your DH some pictures of all the daddies carrying their kiddos, and explain that carrying your baby is a practical thing, and the Bjorn is NOT practical for larger babies, never mind into the toddler years... Slings are a great tool, but honestly, as your baby gets bigger, something that will distribute that weight evenly over both shoulders, and down onto the hips will be so much better for YOUR long term health.
Basically: Good carrier - $100, not having to pay a $2500 deductable on shoulder surgery... Well, he'll get the idea