The thing about RM9 is that it becomes so easy that you don't even need to ever go into the shop after the first playthrough or two, yet again because of the way the game is constructed. Tricky move on Capcom's part, but they managed to find a way to make it so that the game is actually easier than it's ancestors, yet still manages to retain the feel of the older games nonetheless. You don't really need to have as much twitch reflexes compared to the older games, but most people don't even notice.
RM&F has plenty of points that surpass the segments in RM9 that could be remotely considered difficult, upgrades or not. The GBA version of RM&F is even more difficult if you factor in the less intuitive controls and limited screen size.