From what I can work out the variator was a poor marketing attempt at a system like the Jap VVT/VTEC/MIVEC systems. But putting it on one cam only is totally pointless, as it means at only one point in the variator range is the cam actually at it's optimum timing profile with the exhaust cam, the rest of the time is out of the ideal range.
The variator actually operates as such.. It gives zero valve overlap at idle (for emmisions) and switches to maximum overlap for maximum torque in the midrange, and then switches back to minimum overlap at high RMP for maximum power. Otherwise if the valves were still at maximum overlap due to the gas speed, you would end up with fuel air mix leaving the exhaust.
I don't think it is there as a marketing excersise. The VTEC system is totally different to the Alfa system. On Honda engines the actual valve lift changes and boost high speed power, where as the variable cam timing is there to give more mid range torque. The 2 systems are not really comparable.
By using fixed cam timing the engine will only be most efficient at 1 engine speed, where as with variable cam timing the timing can be tuned to suit the RPM bythe ECU.
The 1.6 litre engine fitted to the 147 comes in 2 ststes of tune, 105 and 120PS the 120 PS uses a cam variator, and had 15BHP extra, as well as giving basically the same cam timing.
I am not saying your fixed cam timing engine won't work it will just be a lot more peaky than a variable cam timed engine. You may also have problems with emmisions if you use the standard cam profile.
If you use a high lift cam with the varaitor though you can have problems with the higher lift causing the pistons and valves to collide.
The concept is explained here
Variable valve timing - Wikipedia, the free encyclopedia