You can install the card yourself, no need to send every board for installation. However, there is a common defect on SMD-Amigas called "micro-cracks": The computer appears to work normally, but as soon as you plug something on top of a PLCC chip, the pins are bent inwards. If there's a micro-crack on a pin, it will lose contact with the mainboard, maybe causing the whole computer not to work.
The ugly thing about this defect is that it appears like a defect of the accelerator: The computer works without (pin has contact with mainboard), but if the accelerator is installed, the whole computer does not start. This is where SMD soldering comes in: The 68 pins of the 68000 CPU should be soldered with fresh solder, avoiding to apply solder to the sides of the chip.
I'd expect that at least one out of ten A600's have this kind of defect - be it due to low Commodore production quality, previously-installed accelerators or just the age of the machine(s).