The original questions were if there are some electrical difficulties and if it is feasible.
The answer to the first question is yes, there are some electrical problems, and up to 10 times the fundamental frequency minimum to have clean signal edges, so this normally requires both length and impedance matched traces. Of course, you can hack things like above, but don't expect it to work flawlessly: I doubt the manufacturer would have taken all these precautions if they were not necessary for reliability. Try by yourself to put a 2GSPS+ high-end scope in glitch capture mode if you have the opportunity, and you will see that these kind of events may actually happen with a bad design.
As for the answer to the second question, don't forget that addresses are multiplexed with RAS/CAS, so it looks like A13 is not required to double the capacity: the main Wiki page suggests to replace the original 16Mbit x 16bit chip by a 32Mbit x 16bit one, so this might be possible.
But in my opinion, replacing the SDRAM chip completely is a better option , but of course, this requires a hot air station.
(Last edited by Squonk on 5 Sep 2012, 01:33)