Hi Gary,
You posted this in the Quantum Mechanic forum instead of the Photomechanic forum. There is much less traffic here and Kirk does not check it as frequent either (you'll normally get an answer within the day).
Anyway, as you found, the catalogue function is currently under development by Camerabits. Once its ready, it will be an add-on product which you'll need to purchase separately. From the little I know of the product (haven't seen a glimpse of the real thing yet), it is going to be one of the best cataloguing solutions there currently is. More flexible and most likely tons faster than Lightroom too.
Even though you currently have Lightroom, Photomechanic does have benefits (speed, use of meta data variables, code replacements, etc.). Because it currently lacks the catalogue functionality, there are of course also things you van not do (as easily) as in Lightroom though.
Depending how deep your current workflow is currently integrated with Lightroom, switching (for the browsing, culling, tagging, metadata editing, …) to PhotoMechanic may or may not be a good option.
Hope this helps,
Hayo Baan