Yeah, it could go either way! It may also be a case of choosing how many layers to use - one might just give the text a tint and leave it bright while making the background browny/purply, and more might make the background closer to black but the text harder to read.
I'll give it a try and report back anyway. Reporting back may take months though - my current project list is huge and my bank account doesn't yet want to stump up for the PCBs, panel and misc sundries, but if it comes out nicely it'll help other people out on here.
Regarding compatibility, I *thought* I'd checked, but I've gone through so many different tabs and websites that they all blend into each other, and the description doesn't show HD47780 anywhere, so I guess I missed it. The dimensions match and the circuit board looks like the standard type, but I'll have a dig around to check the compatibility.