The SPU is an old school design - dating back to the 1950's - but over the years many innovations that Ortofon introduced in more modern designs have been incorporated in certain SPU types. As a result these have a more modern sound, but also cost more.
Your preferred 'big and bold' presentation actually fits the SPU as a species pretty well, but the basic models are also rather crude, especially the ones with a conical tip. These have an almost religious following - not unlike the Denon DL-103 - but if you value audiophile capabilities like full frequency extension and reproduction of micro details and spacial information, these are very limited devices.
The 'higher end' SPU's - in some way a contradiction in terms - attempt to bring these typical audiophile aspects into the SPU design, while remaining true to its origin. The Replicant 100 tip (a variation on the Gyger tip) is capable of more detail retrieval than a standard elliptical stylus, let alone a conical one. This is why the SPU Royal and the earlier Gold Reference sound far more modern that other SPU's. The later SPU A90 and A95 Anniversary models have incorporated some innovations like SLM for lower resonance and less coloration. They also have a more modern sound, even while retaining a regular elliptical stylus.