I hear ya, the OCD/desire for standardization/up to date FW would bother me as well, what I can say w/ a high degree of confidence is that v19 was SOLID, I don't think you are gonna see any performance/stability gains that will be earth-shaking but I am sure there were some bugs/features fixed/added.
EDIT: Can SM give ya another .zip bundle (or whoever that was that you acquired that from) of the v20 .bat setup that should be compat/silky smooth for your card...else yeah I guess throw that 3008 HBA at it :-( or at me :-D