I recently tried the 9 and hated it.It would be ok for surface mining but deepcore ..the hard point placement makes it a pain to aim your seismic charges.I went back to using my Python.If you REALLY need a fighter bay equipped ship for mining use an Anaconda.As for the 10...to big an investment on a maybe .
You have missed the golden times of mining when a ton of void opals sold for 1.6m.
Today it sells for 600k. Low temperature diamonds still sell for 1m if you know where to sell them.
But it can still be worth it.
And to be honest, besides the profits, mining is really a relaxing task.
I use a Type 10 for it. The hardpoint placement is much better then on the Type 9 and it has enough of them to pack all necessary gear and leave room for some defense.