If you have several VFTs, then I say do try and experiment, but if I were you I'd rather not use rice water. Use it on other plants instead. Maybe even nepenthes if you like, but you don't want to add another "variable" on your VFTs.
I haven't really encoutered this theory/technique here in the Philippines, not from Chinese nor Filipino. Interesting, but not for me to try out on my CPs.
TTFN
Arvin