I love when people with no tech knowledge try and tell other people technical(if you can even call them that) reasons why things don't work.
The only point he MIGHT be right on is that Xbox couldn't do an exact replica of Metroid. Metroid uses alot of post processing effects(the warping on charge shots for example). It's my understanding(and I may be wrong), that the Xbox isn't well built for this sort of thing. I would be wrong, however.
It's hard to give any real way to discredit what he says since he really just makes a bunch of claims with no backup. So far as I know, the GCN has no texturing advantages over the Xbox aside from a pretty good compression scheme, but the Xbox most likely would more than make up for that in terms of memory capacity.
The only way his argument really works is if you make the assumption that no alterations are made to the code of any game to make it run on the other system, which is an absolutely boneheaded argument, as any decent game has a fair to large amount of it's code written in assmebly, which is, I beleive, hardware specific.
EDIT - Also, I should point out that to say something "specializes in water effects" is about as silly as saying something "specializes in making things look like paper". There are about a million different ways to make water, and none, to my knowledge, are more easily doable on the GC than Xbox. It's all programming tricks, and up to a certain point it's more about being savvy and coming up with a creative way to make water look good than using some sort of built in hardware trick.
About the blood splaterring on walls, all you have to do for that is to cause any collision between a blood sprite (assuming sprites for blood...haven't played RE4) and a wall cause a decal of blood on the wall. It's not novel or new in any way shape or form. It's essentially the same idea as having a grenade leave a burn mark on the ground/wall. These effects have been here since the original half life.
