yes, i agree, that in an system with price inflation people have to argue for higher salaries to get more or less the same while a stable currency or a demurrage based currency prices may stay more stable, therefore employees don't need to argue to get inflation increase of their salary.
To the other part, lower wages must not lead necessarily to less productivity, or higher prices, most likely its the other way round, lower wages would lead to more employment, because less cost and lower prices, because less money too spend (not counting the money inflation itself).
What an UBI woul