I know what you mean there, Tim, but I've never been a fan of that method really.
There's a 100 year old barn directly behind my house that has braces inserted into extra long mortises, and I just don't like the whole system that well having seen it first hand.
Personally, I like the look of a refined entry lap dovetail brace, and some of the examples I have seen in my study of Swiss buildings make this joint quite attractive. The Swiss have a tendency to make everything both wonderfully functional and elegantly beautiful.
That said, I realize that the mortise and tenon has certain advantages over the lap dovetail. It really depends on what the joint is designed to put up with as much as anything. Obviously if your joint is not expected to be under heavy tension then you do not need to engineer it for tension, and a lap joint in compression might have more of a tendency to 'pop out' of its housing.
