I see from your earlier pictures that you have the Ducati Performance race exhaust, which comes with its own ECU. When you turn on the ignition, does the welcome message say 'Monster 1100 Evo DP' or just 'Monster 1100 Evo'? If it shows 'DP', then you've got the Termi race ECU, which disables both the lambdas and servo valve. (It's likely that you do have the race ECU, otherwise the CEL would be lit following removal of the lambdas and servo.)
Even though the DP ECU is supposedly matched to the Termis, it still doesn't give particularly smooth fuelling at low speed, as you've found, and you'll still benefit from a Rexxer reflash courtesy of Neil at Cornerspeed.
As for the servo valve itself - yes, in theory it may present a slight restriction but nothing worth worrying about. I changed the mid-section to remove it and I couldn't detect any change in sound, performance or fuelling - it just looks better!
