There were several other GBA flashcarts as well, though the market eventually weeded out most of the companies producing them. I purchased one of the early visoly carts from Lik-Sang. It was pretty solid, but the lesson I learned was that it was better to wait. The Flash2Advance and EZFlash Carts were much better, and much cheaper.
If I was going to buy a Slot-1 solution early on, I would by from a proven company like EZFlash, M3, or SuperCard... Time will tell if these rebranded knockoffs will be worth the effort to get them.