I've heard bad things about most 3 in 1's. I don't have any personal experience and I want to believe that they would be OK because they are inexpensive and don't take up a lot of room. I've heard that they perform both functions OK but don't perform either function up to the level of a stand alone machine.
If you want to go CNC, again consider:
http://www.tormach.com/
If you want to try 3 in 1 consider:
http://www.shoptask.com/
Really it comes down to size. A good place to look for a huge variety of mills and lathes would be
http://www.grizzly.com
or for the super budget machinist (read...buyer beware)
http://www.harborfreight.com/cpi/cta...264&pricetype=
If you are seriously considering converting to CNC, I would look into the tormach or the CNC options with the shopmaster. Grizzly even has a nice looking Knee CNC (The controller alone would be around $8K). I've been having a hard time finding a decent turn-key controller setup for under $6K. Both the Tormach and Tri-power offer a full CNC system for around that amount complete. You could build a system for way less but you really have to do your homework and then it seems like you end up with a bit of a half baked system.
As far as unobtanium metal cutting...it seems to mostly come down to the cutter. You just have to take things slow and expect certain metals to wear the endmills faster than others. Again, I'm still just figuring this stuff out but I've been where you are not too long ago so I can at least share my experiences.
good luck.