I've been trying to decide what CNC to get for the last 6 months. It's doing my head in as it's a big investment and I don't want to screw up.

I was originally going to get some sort of mill and convert it, however, I want to start making things now, not spend the next year building a cnc.

I saw one of these Sieg kx3 on the weekend and was impressed.
My only worry is the spindle speed seems a bit low. 5000rpm max. Looking at a speeds and feeds chart for carbide tools in aluminium.
3 - 6 mm dia = 10,000 rpm
8 - 12 mm 8,000 rpm
14- 16 mm 6,000 rpm
18 -20 mm 4,000 rpm

Would it be a problem?
Is there an upgrade motor?

Cheers, Marty