With that amount of bread I could be.
You'd need to switch vans at some point, sure. Once you do that, you could have a good amount of headstart.
Also remember, Walt is clearly in big *** trouble with "somebody" breathin down his neck, hence the need to move his money asap. With or without even knowing it's the DEA, Walt has other things on his plate, limiting his moves.
Imagine driving back to that shop and he's in cuffs already. You coulda been 100 miles down the road already.
I'da been gone. Me, personally. That's fine the rest of you are scared or whatever, someone sends me to collect their millions, they won't see me again. That's just me.