Hi Mac
The major issue with GMAW is lack of fusion defects. Technically in spray and pulsed spray transfer this should not happen, but unless there is relatively tight control on the welders, you will always get the guy that goes to dip transfer because it is easier to control. This can easily lead to LOF defects. I do not know what product you are making, but in the case of relatively critical products, many companies will not allow the use of GMAW, for this precise reason. Obviously if you are making a product that does not really have end-user QC involvement, it just becomes an issue of making sure that the systems in your shop are such that you get good results. This can certainly be achieved, as long as the right procedures and discipline / motivation is present.
Regards
Niekie