USB SmartCard 64M is relatively easy to find but no SD slot equals zero convenience in MultiROM - Everdrive GB is indeed the most modern and convenient solution to date.Everdrive GB for GB/GBC and Ez Flash iv for GBA. There are some others, but they are either performing worse than these or they are hard as hell to find one to purchase.
I recently covered the Everdrive GB in the Temp's Review Center, it's a flashcart for Game Boy/Color games, you can read the review here. As far as GBA games are concerned, I suggest hunting down an EZ-Flash IV, it's the best you can get unless you'll miraculously find an M3 Perfect (doubt it ).
ez iv unfortunately uses MINI SD (NOT HC, you need to find either a MINI SD card or a good MICRO to MINI SD adapter)
I agree, both original hardware and emulation have their benefits. When I want to "improve" the game by playing at an increased native resolution (especially important with 3D polygon-based games) or when it's simply more convenient I emulate, when I want the real, genuine retro experience of the games I play on the original platform and no emulator can really replace that blast from the past feeling. If you want to play the games the way they were meant to be played and don't feel like walking around with several cartridges in your pockets a flash cart is a good solution.*Snip!*
I agree, both original hardware and emulation have their benefits. When I want to "improve" the game by playing at an increased native resolution (especially important with 3D polygon-based games) or when it's simply more convenient I emulate, when I want the real, genuine retro experience of the games I play on the original platform and no emulator can really replace that blast from the past feeling. If you want to play the games the way they were meant to be played and don't feel like walking around with several cartridges in your pockets a flash cart is a good solution.