GanFETs seem to be ideally suited for high frequency and ultra-high current applications. The OP hasn't really indicated that their application warrants this technology, unless it's a class assignment.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
Google says that there are bespoke Gate Driver ICs for GANFETs. So inserting them into an existing design should be "straightforward".
Beware of more / higher frequency EMI from the corners of the faster switching speed. The device might fail EMI qualification testing if this wasn't addressed during the detailed design and prototyping.
Also, if the designer wishes to crank-up the switching frequency to take advantage of the faster transistors, then the main inductor might have to be redesigned to be optimum.
If you're using an H-bridge Buck-Boost design (a la LTC3780, which is the coolest thing ever), then all four of your new transistors will be equally fast. But if you're using a simpler design with a diode and then you crank up the speed, then check diode speed implications.
Disclaimer: I've not been anywhere near this topic hands-on, so these points are worth what you pay for them. Just suggestions based on my other experiences.
