I'm jumping the gun here but...
The person who would notice the quickest is also the person who would be willing to pay the least. A collector who knows his stuff, will not pay the spectacular prices at auctions anyway. He is going to find a "correct" Galaga some other way. RGVAC, or a local OP, or another collector, etc. The buyers that spend the dough are usually the least informed (like me

) and would pay big bucks for that galaga even in a dynamo cabinet, to later find out that they got the shaft.
There is always the exception, but I would say that this is pretty standard.
(I personally would rather have a nice Rally-X cabinet than a Galaga. I just play Galaga on my TV with my 6 year old and a Jakks controller

)