I have a mesh Joe Rocket Phoenix jacket and it does have a waterproof inner liner. That said, I am a new rider and I've been told by very seasoned riders that it is a royal PITA if you hit rain to stop, take jacket off, put/zip liner in and put jacket back on - then reverse when rain clears. I can totally see that. They all say to get a set of
Frogg Toggs and if you hit rain you just slip it over your jacket (and pants if you want), then simply take off. It makes sense to me and I'm ordering a set. I'm sure there are many seasoned riders here with similar or very different suggestions. But if you have your heart set on a particular jacket, get it and use the Froggs and don't worry about the liner.