The Nibbler XL has a honeycomb diffuser below the mouthpiece, dunno if I'd call it a true splash guard. I've certainly never had issues inhaling water. I use it on my Hercs about 99% of the time. My weak throat drastically prefers moisture conditioned vapor and being able to judge the thickness of vapor and the strength of their inhale is incredibly helpful when guiding friends or newbies to use the herc.
*Edit: So I just cleaned my Nibbler XL and took a picture through the bottom so you can see the honeycomb diffuser. There's still a bit of water clinging to the honeycomb in the pic.