I don't need the SRX in a BK-9 personally, I just think it would upgrade it substantially. I already own the Integra, so the only thing I would wish is to use more than 4 SRX boards simultaneously (so, e.g. having more SRX expansions in an updated BK-7m would be 'nice to have').
But meanwhile, with my Yamaha MoXF including flash, I really have more than enough space for symphonic and other high-quality samples. I just downloaded 'Garritan Personal Orchestra Lite' for Motif XF yesterday.
However, comparing the SRX 04 strings board: even if it is from 2002, some of its sections are even slightly better than in the Garritan library! I always found that everything Roland offered as expansions was about 10 years ahead of the ROM sounds of synthesizers released at the same time.
BTW, I don't like the idea of using computer software sounds live.
And regarding the Fantom XR (I had one shortly, very hard-to-read display for live use): don't calculate the price of the unit alone, add what you would pay for used SRX boards, still traded for more than 150$ a piece: you end up at the price of an Integra, and you don't have the over 250 supernatural acoustic sounds. When I sold the Fantom XR together with some SRX hardware boards, the sales revenue nearly financed the new Integra - so I don't regard the Integra to be expensive at all.