You sure you can't run Desmume X432R in WINE on OSX? Works fine in WINE for me (32-bit Slackware, not my main OS, just a testing ground :p). If anything, you could dual-boot Linux and run it in WINE (convoluted, I know, but it would work) if you wanted to avoid Windows. It runs without a hitch for all the games I've played so far. 
Zeromus said he is in the process of implementing scalable internal resolutions in Desmume, but he is trying to implement it much more cleanly than the author of the X432R fork. You have to understand that the X432R author is hard to contact (and speaks little if any English from what I've heard, he/she is Japanese apparently) so it's not like Zeromus can just get a hold of the author and ask things like "Why did you do this here? Why is that variable doing this over there?" Essentially, there's a lot of 'foreign' code that the Desmume team has to review, analyze, reformat (to the coding standards the project has), and then optimize so that it can nicely fit with the rest of the Desmume project code. It's not a small patch such as adding a new pixel scaling filter or a new GUI option, and the situation isn't helped by the fact that neither side (Desmume and the X432R fork) is (and can't really) talking to each other. The code is probably there because it's being tested and developed, but still effectively not ready to be used, for the time being any way. I know a lot of people in the emulation community have been clamoring for Zeromus to merge the changes, but it's not an arbitrary or trivial matter from the perspective of an emulator developer.
Having said all that, Desmume X432R is a wonderful thing to have in the meantime. To me it seems like the best solution and how OSS should work. While waiting for an official implementation, someone went ahead and added the feature on their own. They're free to do that (via the GPL), and we're free to choose to use it or not. The official implementaion will (or should) come with less bugs than X432R and be much faster (X432R is notable slower than regular Desmume when you start increasing the IR). Were Desmume closed source, many of us would be still be waiting. But for those of us who can't wait (me
) we have something to fill our needs.
Zeromus said he is in the process of implementing scalable internal resolutions in Desmume, but he is trying to implement it much more cleanly than the author of the X432R fork. You have to understand that the X432R author is hard to contact (and speaks little if any English from what I've heard, he/she is Japanese apparently) so it's not like Zeromus can just get a hold of the author and ask things like "Why did you do this here? Why is that variable doing this over there?" Essentially, there's a lot of 'foreign' code that the Desmume team has to review, analyze, reformat (to the coding standards the project has), and then optimize so that it can nicely fit with the rest of the Desmume project code. It's not a small patch such as adding a new pixel scaling filter or a new GUI option, and the situation isn't helped by the fact that neither side (Desmume and the X432R fork) is (and can't really) talking to each other. The code is probably there because it's being tested and developed, but still effectively not ready to be used, for the time being any way. I know a lot of people in the emulation community have been clamoring for Zeromus to merge the changes, but it's not an arbitrary or trivial matter from the perspective of an emulator developer.
Having said all that, Desmume X432R is a wonderful thing to have in the meantime. To me it seems like the best solution and how OSS should work. While waiting for an official implementation, someone went ahead and added the feature on their own. They're free to do that (via the GPL), and we're free to choose to use it or not. The official implementaion will (or should) come with less bugs than X432R and be much faster (X432R is notable slower than regular Desmume when you start increasing the IR). Were Desmume closed source, many of us would be still be waiting. But for those of us who can't wait (me
) we have something to fill our needs.