I don't know what your experience with Virtual Console has been like, but the game doesn't have weird frame rate issues or glitches introduced by the emulator.
There are minimal differences between the original and the Wii VC release, certain spell effects had their flashing effects tuned down or removed as it could cause epilepsy attacks to people vulnerable to them, or just to reduce eye strain.
That's something that has been done to many games that have been rereleased.
Besides that, and one word changed (bugger to pest) there's nothing else different from the original game.
But then again, you have homebrew emulators to play it and they should play it fine.
The only emu I know it has issues with it is Zsnes and that's old and on PC only.
About GX, the only thing I know is that this fork is more geared to accuracy, and some games might have frame drops, and RX put more weight in frame rate, but the accuracy differences should be small and on specific titles.