I don't have any experience with B&C, but I have a Brown and a McMillan. The McMillan is far superior.
I should qualify that. The McMillan is a finished dropin for a Ruger Ultra Light. The Brown was an unfinished, primed, Pachmayr Dec installed, swivels installed, for Rem 700 ADL (I was trying to save money - same price as McMillan drop-in). I had it bedded by a local gunsmith. It has been nothing but a problem. First of all, it just didn't fit the action at all. When bedded, all kinds of problems surfaced. It sat too deep in the receiver mortiss, but the barrell was still misaligned. So, I had to grind off the rear tang screw, shim that area, and sand off the bottom of the trigger itself to keep from rubbing on the trigger guard. The receiver still sits fairly deep in the receiver mortiss, but the barrel is still too far out of the fore end. Was having all kinds of problems with the bolt release and trigger release.
Purchased a Jewell trigger for the subject rifle. When installing the Jewell, I found that the trigger was rubbing against the inside of the trigger guard cutout. Moto Dremelled the inside of the trigger guard cutout and things looked better.
Upon further investigation, the glass bedding was done without making allowance for front, side, and bottom clearance. Used the dremel to remedy this situation. Everything is much better now.
The rifle is a Rem SS 700 ADL .300 Win Mag. It was one of those SS ADL Mtn Rifles that Remington produced in limited quatities. I had the barrel fluted, and with the Brown stock and Leupold 2 1/2 x 8 Vx 11 -- It weighs about 7 1/4 lbs with scope, ammo and sling.
It is great to carry, but not real pleasant off the bench. This is my hunting rifle -- it's been a pain, but still my "go to" rifle. It's light, has an excellent trigger (now), it's weather proof, and is reliable (now). My son keeps trying to get me to let him use it -- he has a Win M70 that weighs about 10 lbs with bi-pod.
Bottom Line -- Spend the extra money, and get the McMillan. You won't regret it.