Huh, that's crazy. I just checked, and the size of my title folder is barely 166MB (and, using a 2GB SD card, there's still 1,2GB of free space). Would this already be hitting the max combined size?Oh, it doesn't, although I did find the text confusing too - this app doesn't even access the internal flash, and "free DSi space" means "the official capacity of an empty twlnand partition - the size of the files on SD that are located inside folders with names that are normally used in twlnand" (in fact I don't think it should subtract /photo/ since twlp is a separate partition)
And yes, there is a fixed limit about the combined size of DSiware - in fact it's more surprising that it starts at all with a 2 GB twlnand without filling space to less than 256 MB free!
I think I actually used to have more DSiWare on my system back in the day than I can fit on the SD card right now before it shows the "An error has occurred" screen, as I still have to install at least 10 titles before I can play all of the games I sent to my 3DS on my DSi again.
I know I could just play everything through Unlaunch or Twilight Menu ++, but it just isn't the same without the official interface.