you should keep or buy another 1.4.1 DSi, in case one day you come across a different flashcart. the other flashcarts have advantages besides just running on latest firmware, such as different bootloader icons, new features, more options, nicer menu systems, etc.
for example, Wood R4 runs homebrew better than supercard. and supercard is not directly compatible with EZflash 3-in-1 without a 3rd party app. also supercard dosent have a proper "File List" mode with smaller icons.
i think the only carts that work on 1.4.5 are Supercard and R4. of cource, a old DS Lite runs everything including GBA carts.