Yes, the math is clear. Downtown Grand's VP is stingier than its competitors downtown. No getting around that fact.
But is it really that terrible? Imagine your game is quarter JoB. If you hunt around, you can find it downtown paying 9/6, which is 99.54% payback. At the DG, you'll only get 8/6, which is 98.39%. But how bad is that really?
Well, at $1.25 a play, you'll lose an extra cent and a half every game playing 8/6 instead of 9/6. At that rate, it'll take you quite a while to lose an additional $20 at the DG. 1,391 hands, to be exact. That's at least 3-4 hours of intense play for most people. Plus, at DG you can play it at a nice bar and get good drink service. Other than possibly Main Street Station, you may not find 9/6 at a bar downtown. Over the course of 3-4 hours of intense play, could good drink service and the nice, relaxed, upscale atmosphere of DG be worth $20? Maybe, at least for some.
Now, I'm the cheap sort and don't value fast drink service very highly, so I probably am going to find that 9/6 machine at a dumpier downtown casino and play it instead.
But really, in the great scheme of things, it's not brutally expensive to play 8/6 JoB at the DG.