I don't think I"ve posted here before, so I don't really have any 'cred', but I do have to say that I"ve been a faithful EZ customer for a while. The EZ2 I"ve got is great, which is why I got an EZ3. At first, the GBA support was crap, but with updates and plenty of time, it's become the best GBA cart on the market.
Of course, I didn't go out and by the EZ4 as soon as it came to market. The EZ team, as great as they are in the GBA market, haven't really proven themselves in the NDS market, and I certainly wouldn't expect their first outing to match the year or more of experience the M3 and SuperCard folks have under their belts. Will the EZ4 get better with time? Most likely, they will. Will it take a year or so before they have the upper-hand? Again, most likely, if they end up on top at all.
Really, it's kind of like buying the first model of a new type of car. Personally, though I am highly in favor of the EZ brand, I bought a SuperCard for the price and compatiblity. I've already got a great GBA card, and the SuperCard takes care of all my NDS needs.
It's all about managing expectations. If you were one of the folks who bought the SuperCard when they first came out, you'd probably be really pissed off at the horrible (relatively, of course) support for GBA games. But, they turned out to be at the top of NDS support (in the top two or three, as some may argue). That didn't really come out for a couple of years though, and the EZ team, while slow with updates and such, still do support and release software updates for their older stuff. And, I'm sure, though it'll take some time, they will release updates to get their EZ4 hardware as close as they can to the level their EZ2/3 stuff is at.
And that's all I've got to say about that. Bleh.