As for productivity - we had a discussion on beesource (link?) on this matter. It looks like some beesource members think that long hive is less productive than vertical Lang because "bees expanded vertically". There were some reports from Europe that long hives may produce up to 200 kilos (am I right? 100 kilos for sure) of honey per year, I do not remember details.
> do the produce the same amount as a conventional Lang?
A horizontal hive requires different management than a vertical hive. If you manage both like a vertical hive you will get more from the vertical hive. If you mange both like a horizontal hive, you'll get more from the horizontal hive...