Mac mini and VNC remote performance
Our development team all use Macs. I have personally tried to use VNC both with Apples built in and premium Apple Remote Desktop ($79.99), as well as Jolly's Fast VNC. I had a Mac Pro tower at work and really needed the remote capability, and was able to work reasonably well with Apple Remote Desktop, but when my tower came off lease I went with a Laptop, because the lag and poor display quality were just too annoying. I found that I needed to degrade the display quality in order to keep the performance reasonable, which meant a blurry display.   Overall I found it frustrating and avoid remote access, but it does work, although I would strongly recommend buying Apple Remote Desktop to get the full screen capability. Jolly's was fast but at the time had some bugs that resulted in a corrupt screen sometimes. That was over a year ago, the new version may be better.

There are other developers I work with who think that the VNC solution works just fine for them, so I think it depends a lot on how fussy you are about responsiveness (I am fussy). 

If your previous experience with remote access involves Microsoft's Remote Display Protocol (RDP) then you will be very disappointed with VNC. The RDP technology is superior in both display quality and performance. One of the few things I really miss from the Microsoft world. 

In short, I'd recommend moving to an Apple laptop and then running your Windows virtually. I started with a mini originally, and just ended up moving to a laptop eventually.