If you are impressed by the XP 30 sounds and are interested into buying an arranger, the best thing you can do is to check out the Roland VA 7 or VA 5: they are among the best arrangers on the market and exhibit most of the sounds you seem to like so much in the XP 30. In my opinion, those who love the "Roland sound" are not likely to be impressed by the "Korg sound" or the "Ketron sound", and viceversa. (It's just a matter of taste and personal preference, I guess).
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Korg Kronos 61 and PA3X-Pro76, Roland G-70, BK7-m and Integra 7, Casio PX-5S, Fender Stratocaster with Fralin pickups, Fender Stratocaster with Kinman pickups, vintage Gibson SG standard.