We can weld center differentials here at Jacks Transmissions. We TIG weld them properly preheating all parts first, use an infrared thermometer to make sure we are not over heating the housings, and then let the assembly slowly cool.
Our welds are strong and we have NEVER had an issue with a welded center coming apart.
Problems using a welded center instead of an LSD/VC unit include wearing out tires, drive shaft, CV shafts, and engine mounts more quickly, and slipping or chirping of the tires when turning in tight areas.
The advantage is that you never have to worry about breaking spider gears again.
4-spider differentials are highly recommended for all DSM’s up to 600 HP. A welded differential becomes more appealing with over 600, partially because 600 HP cars are rarely driven on the street.