Just a quick note. If you are playing GBA hacker and are going above the 16 meg mark you will need something other than IPS. Some later GBA hackers went to UPS, personally I would probably go with something in the xdelta or bsdiff worlds (DS hackers tended to go for those).
If you are sticking below 16 megs (either not expanding there or not working on one of the 256Mbit titles) then carry on. There are a few downsides to IPS but most of them other than size are not such a problem as they are on older systems with headers occasionally being or not being there.
Edit and Cyneprepou4uk's choice is good. I quite like https://www.romhacking.net/utilities/13/