Funny you should mention zero tolerance in the military because I used to fly with a serving (now retired) RAF officer FJ Instructor whose colour vision was worse than mine - he was quite open about it and the fact that there were 'ways and means'.
However, I digress and on to the subject in hand.
FAA System -
1. Ishihara or other recognised pseudo-isochromatic plates.
2. Farnsworth or other recognised Lantern Test - 2 lights at a time - 3 colours.
3. SODA - Statement of Demonstrated Ability, i.e. Practical light test at airfield by FAA Inspector
JAA System -
1. Ishihara (currently checking whether other recognised pseudo-isochromatic plates may be accepted).
2. Beynes Lantern Test - 1 light at a time - 5 colours.
3. Holmes-Wright Lantern Test - 2 lights at a time - 3 colours.
Note that the respective lantern tests under the FAA and JAA systems are NOT accepted by the other, i.e. a pass on the Farnsworth will not get you a JAA Class 1 and vice versa.
I love the argument about foreign pilots who do not meet the medical standards for the UK (or any other JAA country for that matter) being allowed to fly in UK airspace. If something did go pear shaped and a serious accident occurred which was put down to colour vision deficiency, who would be at fault?
One other thing, when thinking about going down the FAA route, apart from any flying instructor experience on an approved programme under the J1 visa scheme, without US nationality how would you be able to work in the USA? Surely US airlines are not going to recruit foreign pilots in preference to home grown, regardless of where they did their training.
And as for operating a N-Reg Bizjet in the UK, I think you'll find that the new ANO 2005 states that you still need a JAA CPL to work in a commercial role in the UK.