DGS is an evolved version of the old PCI grading service. David Lawrence Rare Coins(DLRC) purchased the intellectual and physical property of PCI a few years ago and restarted it is a new
TPG. DLRC is a dealer and auction house so as to not have the appearance of saturating the market with their own coins, all DLRC coins graded by DGS have a "D" listed at the end of the serial number to differentiate them from public submissions. From what I have seen DGS has been significantly more stringent in grading than PCI was but one thing they did continue was the Signature Series where experts on a particular series grade and attribute a coin and sign the label, coppercoins is the expert for Lincoln cents. Another nice feature is that any coin graded that is valued over $100 is imaged and placed on their website for photo verification. They have only been around for ~2 years now but I think their reputation will build.