In general an incremental load with qvd's should be faster than sql-loadings against a database.
But it will be depend on various things how much faster it could be and the efforts which are needed for it.
For example, is the database quite fast and the limiting factors are mainly the database-driver and/or the network it could be that the inner join + the few transformations (status + truncating) are faster performed as the same rawdata without any transforming are transferred to qlik.
In this case you couldn't get this step faster with qlik but you could load this joined table with an incremental approach - and I think this is the essential point here - by an incremental loading you need not only load the rawdata incrementally you must also load the transformation-results incremental and by this building a multi-staging load-approach.
For your case it might be a bit expensive to do this but if load-performance is a bottleneck or you could use thes qvd's in other cases it might be worth.