Save your money! Weld the diff and buy LONGFIELDS, I have an elocker in the front of my toy and I havent unlocked it in 2 years, and my hydro is sitting on a self in my shop, don't get me wrong, the hydro helps a lot, but it isn't necessary. The only time you will notice a welded diff is when your on dry road in 4wheeldrive(you shouldn't do that anyways)or all four tires are firmly touching solid slick rock and even then, back up a few more times, so what? Ejs isn't werock championships.
If anything I'd weld the diff even with the stock birfs, I have two toys in my shop right now with stock birfs, 36s and welded diffs, both of which I personally dive and beat on regularly, yes they do break sometimes but its not half as bad as people make it sound. Keep in mind they are stronger than many stock axles out there