I'm very open to the idea of FP+, I just wish there was some sort of information in regards to an official role out date and who will be able to get them. I leave in 41 days so I kind of hope that nothing happens between now and then.
Nothing will happen in that time frame. The last day of the test is tomorrow (Well today, as it's after midnight, 9/24) and then everything will be back to normal until at least next year.
That goes for the Haunted Mansion queue as well, after the end of the test it will go back like it was until there is either another test, or the official roll out. As far as the wait times there go, that was more due to the park having several rainy days this week (Including the opening night of Horror Nights) and an extreme crown re-distribution because of it. I would expect wait times to return to normal this week.
Just because you can pre-schedule a few rides doesn't meant you have to pre-schedule everything. Even though the system is really not that complicated, it is being treated as such, so if you guys can't figure it out, why would you expect the average guest visiting from Chicago, Rio, Houston, or London to figure it out and utilize it? It's not like every single guest who walks through the gates will have Splash Mountain fastpasses at the same time. For a ride like Splash the line might get a bit longer in the middle on the day when it's swamped anyway because people want to ride it, but I'm sure it will still be dead at night when no one wants to get wet. (Even though you don't really get wet anymore).
And keep in mind that you can change your reservations all you want, so if you go to the park and realize that it's empty, you can cancel that Mansion reservation and change it into a Space Mountain Reservation all the way up until your scheduled time (which you can also check/change at any time on your smart phone or at five different kiosks throughout the park). And, with this test, so presumably in the final product as well, you can also book parade and fireworks viewings so you don't have to arrive an hour and a half early to get a spot for the electrical parade (or God willing Spectromagic by the time this rolls out, finger's crossed) in the hub.
There are still a lot of details we don't know, we don't know if there will be a charge, how it will roll out, what the benefits are for Annual Passholders, Cast Members, or DVC members, so with things like that we have to keep our ears to the ground, but other than that it really all seems great to me.