I don't know the 40.1s but have used the 40s for recording rather than mastering.
In the early 2000s a big chunk of my work time was spent recording vocals and mixing the songs for Jim Henson's 'The Hoobs' TV show. It was a sizeable undertaking, 250 x 25 minute shows shot at Elstree, and in the second year the TV sound crew got a pair of 40s about halfway through. I divided the workload between base at Harlow and the soundstage, recording in either place depending on puppeteer availability, and had no surprises using the Harbeths: anything I did on them translated well, and they were particularly good in the vocal area.
On a soundstage day I would record vocals when shooting had finished, and usually came in an hour or so ahead of time to set up - the TV sound crew would have been working all day with the Harbeths cranked quite a bit to hear speech or play-in anomalies as they occurred (the most hated phrase in a TV studio is probably 'one more for Sound!') and it was apparent that, for this task anyway, the speakers were a good fit.