MD Labs seems to be pretty good at picking up some co-infections such as Anaplasma and Mycoplasma. Those are the ones I tested positive for and others I've seen use them. The problem is their Western Blot test for Lyme leaves a lot to be desired. I tested negative through them with only one band reactive on the IgG and none on the IgM yet through IGeneX I had many + bands especially on the IgM. The one band 41 that came up positive though MDL was quadruple + through IGeneX so that goes to show you their test needs improvement as the others didn't show up. I know one person that came up positive through them but a few others did not. I would use IGeneX as they are known to have the best WB test for Lyme hands down. It's not perfect but it's the only one I would use since there are so many false negatives with this type of testing.
My MDL test was covered by my insurance so they do participate in some plans. With IGeneX you most likely will have to pay out of pocket but if you can swing it then that's the way to go IMO.