OP Stated " Thoughts?
Also, is this as great an offer as I think it is, are there better TTs at 15K$ retail price (I cannot/will not buy used) than the SME 30/12A? "
The OP hasn't been exactly met with their request made to learn of a TT that will cost as a New Model $15K and better the SME 30/12A.
As I have a good knowledge of the SME 20/12, as a result of being demo'd it on numerous occasions, I am sure that I prefer a DD Drive and the Models put forward such as the SP10 R and SP 1000R are seemingly on budget to the request made.
The SP 10R with a careful Tonearm Selection 'will' be a Tool with all the capabilities to offer a 'mind blowing ' experience. I have shown how the SP 10R can be produced as a replicant of the SP 1000R for a much more affordable outlay. Adding a $4Kish Tonearm of ones choice to the 10R, and not being limited to the 1000R Arm, will get a TT and Arm for approx' $13K, that will see off most of the competition. Extend the option on a Tonearm to a used item at a $4Kish cost and there is a serious TT for the money, not much to contend with it up to a £100K, to show where it is with shortcomings. I know this as a first hand experience from regularly experiencing one in use, and having been demo's substantially expensive TT's over the years.
It seems like 'mind blowing' and 'Outperform Digital' and worth 'Stretching to the Purchase Price for a discovered Item, as an attempt to maintain the experience', is the assessment formed during and following the OP's SME encounter.
As the OP has informed of their inexperience around all things relating to a Vinyl Source and their (knowing next to nothing about about Set Up). I am eagerly keen to direct their attention away from a Belt Drive design and the continuous complexities to the attentions required to keep it on point as a function.
The New DD TT models as referred to, is a much more user friendly experience and will be much more suited to an inexperienced individual, the value of the DD TT will be easily attained and maintained, not such a story with a Belt Drive.
The reference to the SP10 MkII is a more awkward one to throw into the line up.
The MkII is used (not the OP's wish).
The MkII is very capable and with serious potential, the route is made clear with an outline costing. Add to the $2ish outlay a $4Kish New/Used Item Tonearm ( The OP might be excited about a used item SME V 9" or 12"), there are very good options on Tonearms at this price point. There is only one outcome, a TT that will standout in a comparison to its later produced sibling models, and as made known, as the experience of one SP 10R / Modified MKII Owner. The MkII in a very early stage of receiving modifications was capable to put the Newer Generation 10R out to grass. Once more I am experiencing the MkII undergo modifications that are picking up where the mod's are quite evolved and notable for the impact made and improvements perceived. I have no doubt the SP10 MkII I am listening to, to assess the works undertaken, is improved over the 10R I visit regularly.
When the P'holz Chassis MkII is in use, which is imminent, the 10R will be sat aside it for assessment, the 10R Tonearm will be used, also the 10R Tonearm can be be mounted on the P'holz Chassis, if the owner wishes to detach the arm from the Standalone Arm Pod and do this.