FAR 91 does not require equipment suffix either for VFR or IFR. In your
above quote (reference?) it says "recommended" (not "required") in
order for ATC to have more info for the IFR flight since ATC is more
likely to deal with IFR than VFR. Nowhere it says that equipment suffix
for VFR is not required or not recommended or forbiden. FAR 91 does
mention use of "full blown IFR GPS" for VFR use. When ATC does deal
with VFR the suffix may be helpful - as was in my one case with a
briefer.