I'd like the lunchbox locker better myself. This way you do have a chance of breakway instead of breaking an axle or U joint. Something has to give and let's face it, 10 bolt or Dana 44 isn't the strongest units so I'd prefer my carrier to breakaway first. Chances are if you're on dirt , mud, gravel, snow or ice, and maybe even wet pavement, it's not going to breakaway anyway. The tires will just slip and carry on. The mini spool is full time locked up and doesn't break away at all. C4 has said to weld spiders and then just lock in 1 hub in situations where you might break an axle. True that will work too but I'd rather just have both locked in and if one axle needs to breakaway for a sharp turn or on some hard dirt where you have good traction then it can do so.
The other thing to consider, it how big of a tire you're running and how much horsepower??? I'd imagine you're going to be OK on dirt, gravel, mud or loose surfaces, but for example. LockRight lockers are rated up to 35in tire or 350hp. Granted, that's on dry pavement. I've heard the Yukon lunchbox doesn't even hold up well to 35in or 350hp. It's more less for an OEM application and has great results that way.