Yeah, but it's not really a matrix 12 right? 
I know a very good technician here, he fixed the 4 voice version, I'm not scared when it comes to vintage, especially with his backup.
What in life is not a time bomb, eh?
I wouldn't buy that matrix 12 too, I haven't the right skills yet, but IMO cooling the lust with other synths/substitutes is not the way to go, if you want the matrix or the xpander then grab the matrix or the xpander 
the more you spend on other stuff the more further away you will be from the original goal (use this method for other stuff in life) ahaha
My two cents.
The 2 voice and 4 voice synths are still in production.
This is the one he repaired:
http://www.vintagesynth.com/oberheim/4voice.php
Hey I'm just quoting what you said:
I am more interested in how it compare with Oberheim Xpander for instance.
My conclusion is that none of your options compare to an xpander or matrix 12 and that's the whole point of this discussion.
I am only intereted in the new PRO and digitally controlled versions, that is the old one.
Xpander was just one example since it fits well for ambient music, the SEM series is not as much used for some reason,
but from what I have been hearing about it it sounds very good...
I have no problem that it sounds different the xpander or matrix it is not like they are some ultimate benchmark they just sound different..
Anyway I will never buy xpander or matrix again, as I said..the older they get you more likely is it that they break down.. in my country it is not many people who can repair it if any.. and it would be expensive. the New Sem series I think will not break down any time soon..they seem rigid.
