I agree with chrisdoran1. I've definitely been including 'Bucks' as in the example given - Farnham, Bucks. I haven't been keying the 'Mdx' (and variations) where the parish is given as say 'St Leonard, Shoreditch'. But when reviewing, if someone has included the 'Mdx' and keyed 'St Leonard, Shoreditch, Mdx' I've left it as is. I'm sure the database search parameters will cope with the 'Mdx'. Conversely - I think it would be really helpful for researchers to be able to see/search for Bucks, Buckinghamshire etc in their searches.
Just my opinion.