This is a slightly strange playtest report.
I had created a Level 4 Warpriest of Desna. I also built it as a Ftr 1/Cleric 3. After a lot of dithering I decided that I just couldn't bring myself to give up the better travel domain abilities that I get as a Cleric (increased 10 foot movement speed, domain spell of longstrider).
That is probably more evidence that the travel domain is overpowered than evidence that the Warpriest domain is underpowered.
One thing that I didn't really like is that the 2 characters "felt" almost identical. Both were very martial clerics of the same Diety.
If the final book had a feat to turn a Warpriest Domain into a Cleric domain (ie, get access to domain spells AND get any additional abilities) I'd
1) Have taken that feat in a heartbeat
2) Played the Warpriest in a heartbeat.
3) Still considered them more or less balanced. With the WP being more martial and the Ftr/Cleric being better at spells and healing.
Without that feat the Ftr/Cleric played significantly better than the Warpriest would have. Although a huge part of that was specific to the travel domain
So, I took the L1 ftr/ L3 cleric through the high tier of Glass River Rescue. But I had the Warpriest character printed out as well and mentally decided how I'd play it to see the differences.
They ended up reasonably close but the edge most definitely went to the ftr/cleric.
This particular character was using Thunder and Fang so I could only afford a Cha of 10. So, 2 fervour. Which would have been used only on casting divine favour as a swift action.
With 2 fervour I'd have cast it on the 2nd and 3rd battles. With a slightly different build and a 3rd fervour I'd have also cast it on the 4th encounter.
However, even as a cleric I managed to cast it on the last 2 battles. In both battles, the fact that I had a 40 ft movement speed meant that I oould cast it as a standard and move 40 ft. Whereas the WP would have cast it as a swift and double moved for the same 40 ft.
The group had another cleric so I only ended up chanelling once for 2d6 damage. With the WP I certainly wouldn`t have bothered to do so. Again, this was an option because of my movement speed.
Especially for PFS the ftr/Cleric has the advantage of being more versatile. I can actually channel, I can afford to cast some non buff spells.