I have a X7 and a EzFlash Jr because I want my experience to be seamless and compatible with RTC games, but if you’re really after something for homebrew or don’t mind the added step for anything that supports saves, just get the cheaper one.
No
Not exactly. Some original carts with SRAM would save automatically. You could shut it off and when you turn it on again, your progress would be saved without doing anything manually(eg. Mario Six Golden Coins). In any case, even those games, you still have to do another manual operation on the cart to save the “virtual save”, so the difference is that saving requires an additional, manual step, beyond whatever the game itself requires
If you’re not playing games that save to SRAM, nothing. If you are, then saving just requires you to do it manually, rather than being able to just shut it off and be done, like the original carts would
Just for anyone running across this later, another limitation of the EzFJr is that you have to load a custom F/w if you want SGB to work. The Krykzz cart works fine out the box for both platforms. That said, I do own both, and the EzFlash is a great budget alternative for handhelds if you can get it.