I've always processed them in batches of about 50. For one particular customer (Premium, if it matters) I ran tests, and the further into the list, the slower per item code it became. Also, the renumber screen has crashed on me when trying to renumber a big list. Smaller batches are my routine now.
When asked about SQL magic doing the renumbering, I refused. I'd not risk missing the dot on an i or omit crossing a t (with manual SQL changes). If something goes wrong with the Sage utility, I can blame them.