... Anyone able to assist in the justification of Radial over Tangential? Are there other advantages other than accepting more frames? or are there in fact some disadvantages other than cost?
You can't make a really small radial.
So small extractors are necessarily tangential.
Tangential requires turning the frames round a couple of times to fully extract.
Radial doesn't. Just one spin per hand loading, if its balanced! Massively less faffing around.
For Manley frames, you should use a radial.
But for Ling Heather honey, you need (so I'm told, never had any) to extract Tangentially.
Unless you buy a massive extractor (20 frames?), extracting big brood frames needs to be done tangentially - because they are too big to fit radially - so you need extra 'screens' to temporarily convert your radial to tangential (but such a thing can be done, and its easy - just a bit more spending!) Those same screens could also be used to spin bags of cappings.
Unless you are a real heather specialist, a larger extractor would be a radial. But if you are buying a small one, it'll have to be tangential.