what is your opinion on using a duo 2 core or quad core machine as opposed to the RB1000? which would give a better performance.
If looking at raw performance: With a fast card bus like PCIe and Gigabit ethernet ports, a well designed x86 duo or quad core machine should be much faster as long as there are ethernet drivers in RouterOS. If you look just at clock speed, the x86 machine will win as most are in the 2.4GHz to 3.0GHz range vs 1.33 GHz on the RB1000 PPC. Then you have the advantage of multiple cores. Now that ROS is supporting multiple cores, you have another huge advantage on x86 assuming your application benefits from that.
But there are other places and reasons why the RB1000 is a better choice.
If your concern is reliability instead of winning a drag race, the RB1000 is a single board computer designed, manufactured, and sold by Mikrotik who also happen to make RouterOS. One company, one solution, you can count on support and it working. It is smaller and lighter than most x86 boxes. It will run cooler, quieter, and cost less to run than an x86 box.
A properly engineered x86 system that will be fast and reliable as described in my first paragraph, will cost more than the RB1000. Something like the third party Powerrouter 732 meets the criteria. It uses a 3GHz dual core CPU. It is fast, reliable, loud, and sells for $1400 which is 2 times the price of the RB1000.
I am really looking forward to the Mikrotik MUM announcements where we should hear about their new RB1000U replacement and perhaps other new products.
Tom