This seems to me a bad idea under its current guise and lack of details. But it really comes down to the variables of how fast the favor is disturbed. IMO for this to be viable we would need to:
1. be able to obtain a full bar of favor instantly after saccing if the volume of sac'd items was sufficient, anything extra should go into the pool. This would blend the two systems and allow some folks to do the classic method and some adapt to the new.
2. Favor is often needed right away for certain obvious things like healing, summoning etc. Perhaps when using gems favor would be instant and NOT go into the excess pool. Basically working the same as they do now.
3. Spells should still be based on the favor requirement min to unlock and not be allowed for oversaccing.
4. Proper balancing of favor. As mentioned many folks including myself still use classic even thoe nerfed veggie favor because some forms are just plain a serious pain in the ass to make compared to others, particularly if you have multiple priests potentially using different forms. Metal and wood items for example are still too weak favor wise for the time/energy it takes to produce and calculate the favor generated or used per sac.
5. Side note PLEASE GIVE US A HOTKEY FOR THE GETPRICE FUNCTION since your forcing us to use more complicated, and less determinate items for favor. IE Locks, Yoyo's etc....
6. Favor stored should absolutely not deteriorate. I can see why this might be a thing but perhaps as long as your not moving favor does not decay. this would eliminate abuse for PVP etc, as soon as you move you start losing favor. If favor degrades in any reasouable amount then were just back to wasting favor by oversaccing witch is one of the problems to specifically address.
7. The first favor tick after casting should be larger to potentialy account for failed casts.
8. The maximum favor pool should be NO MORE then 300 to prevent solo'ing seasonal rite spells. Or Rites should require no less then 4 people in chain. Or even easier you cant spend more then 100 favor per cast.
9. Cannot spend a links pool favor directly.
- OR -
Just Reduce saccing times to 5 or 10 seconds, raising the favor cap is the same problem because people will always want to optimize and get as close to absolutely full as possible. This is honestly probably the best solution overall and with the least headache, unless there is another agenda behind the change.
For example: I want to cast life transfer, costs 100 favor. This under normal conditions takes 20 seconds to cast, and 30 seconds to sac for, making cycle time about 50 seconds. If i were able to oversac to say 300 favor with a 50 points per 30 seconds regen then that would allow me to make 3 casts in about 80 seconds per cast average. Thus increasing the time taken to cast by over 50%. (80 seconds for additional casts up from 50 seconds, and saving no time at all on the first sac.). One does not need to be a math genius to see that even this number is inadequate to compensate for the reduction in sac actions. Distribution would have to be in the area of 100 points per 30 seconds to even be close to the same. Even more so to actually be effective at saving any time whatever. Thoe i dont see why we need the action to take less time overall i can see the reasoning and giving folks the option.
On the surface to me this looks like its just gonna make casting take even longer, but it really will come down to how the passive distribution works, but IMO you absolutely need a large or full bar of favor right after sac even if you over sac into the pool. Some simple math suggests that unless the rate for distribution is pretty high then your really just making casting even longer. The rate would have to be something to the effect of 90 favor per 20 seconds + passive gains to even be comperable to the existing system.
Personally i don't see a problem with having to sac for each or every other cast. Please give this serious thought before implementation and don't break casting anymore.
Addition: and just so were clear you say we spend half our time sacing, but thats only the final step in the process of favor production, i dont spam you all up with the numbers here but it takes 2 minutes + just to make the materials for 100 favor before you can even sac it. So reducing the number of sac actions is a minimal net gain even if it were made to the point that 1 sac could give me 1000 favor. In reality near 90% of the time of the "cast" goes into favor production