I have no real opinion on the possible purchases.

Smooth tires on a mountain bike are always an inexpensive alternative to get quicker rolling if you aren't doing true mountain biking. In fact, some early hybrids were not very different than mountain bikes with smooth tires. I have a Raleigh mtb that I have converted to loan to people for rail trail rides, and it has worked very well with smooth tires as a hybrid. For the one I use, the suspension fork was shot, so I replaced it with a rigid fork to savbe weight and avoid energy loss. If the fork was functional, I don't know whether I would have converted or not.

Concerning your other bike... When you ride the Envoy, do you ride on the hoods, or in the drops? Riding in the drops is uncomfortable for many people until they get used to them. In addition, for many riders that use drop bars, the benefit is multiple positions. If you watch a road bike race, the majority of the time you will see the riders riding on the hoods and bar tops more than in the drops... Just something to consider.