Hi @James H. Robinson ,
Thanks for your patience. I got update from Product team that the recommendation is to use partitions. Process the new partitions (Ex: monthly partitions) and delete the old partitions.
And for using PowerQuery M functions, the filter expression in M will fold properly to the data source if it is a data source with compute (e.g. SQL Azure/Synapse/etc.) and be efficiently handled. For other data sources, you have to be careful about how to pull data efficiently.
Hope this helps! Please let us know for further queries and we will be glad to assist.