The OG figures are noticeably smaller than the newer lines. They'd probably line up nicely with Foundry, but they look like shrimps next to Renegade or Copplestone.
Which is a shame, really, as they have a fully developed line including such rarities as Serbians and Italians, plus vehicles, and specialties like signallers, sentries, stretcher bearers and the like. I particularly like the listening posts, which were a very important part of trench warfare but tend to be overlooked in other companies' lines.
However, this is just my opinion. You could try buying just one pack, and compare for yourself! Maybe something unique like the doctor and nurses, which can be used inmany other games if they prove to be unsuitable for your current plans.