Hi Daniel,
In a word, yes. While Haverhill is a nice big organ - and one of the first I acquired in my early days with Hauptwerk - the Armley sample set is in my view worth the outlay. For a start, it's a sample set of an organ with a much higher profile on the international organ scene than the Haverhill instrument. Also, the sampling is very good. It's been a while since I last played the Haverhill so I'd have to load it up again to be sure, but I believe that the Armley sampling has benefitted from experience. A great deal has changed since the days of Haverhill.
Yes, Armley lacks a Tuba, but it was never meant to have one in the first place. If you want a Tuba, then get Hereford (also from Lavender Audio), Salisbury (from Milan Digital Audio), or the Willis Studio series from Silver Octopus Studios.
Armley is one of those sample sets which - to me at least - allows a player to enjoy the sounds of a truly historic instrument from the comfort of home. You may know the lovely Walker organ of 1866 at St John's Cooks Hill. When I played there the late 1970's I didn't concern myself with the stops which it didn't have, but revelled in the ones it did. Just 11 stops over 2 manuals and pedal, and with a Tenor C swell - but it was an absolute delight and privilege to play it almost daily for 4 years. You'll derive similar pleasure from Armley.
Andrew Grahame
Sydney