Whilst it may well be cheaper, in some cases, to follow the route that Moochooser first advocated, it should be borne in mind that the figures listed are based upon the cheapest quotes of various marketing departments and "my mate told me" estimates, neither of which are particularly reliable. They also assume that the average person will be able to pass everything first time in the minimum possible hours. For these reasons, the figures should be treated with extreme caution. It should also be noted that, as silverknapper pointed out, the original post did not compare like with like - the figure of £56,500 did not relate to a minimum cost modular course in the UK, which can be had for well under £30,000.
Also conveniently ignored is the attitude of JAA airline recruiters to pilots with only 10 hours (or less) experience in JAA airspace. In his original post, Moochooser stated "....you lot who say the name of the school means a lot can't deny that a holder of a frozen ATPL, with those type ratings, would stand a far better chance than a fresh graduate from one of the rip off UK schools". I have to say that most JAA airlines would favour the fresh graduate (who they would, in any case, bond for the appropriate type rating) over the holder of a MPA type rating but little relevant experience.
Before assuming that conversion may be achieved in the minimum time, having taken the cheapest options towards FAA qualifications, it might be worth taking a look at the FAA Practical Test Standards and comparing them with the CAA's Standards Document 1.
As Alex suggested, and contrary to Seaweed Knees' assertion, NDB tracking is not a mandatory part of the FAA instrument rating, the PTS lists the minimum radio navigation equipment as that necessary "for the performance of two of the following nonprecision approaches: VOR, NDB, GPS, LOC, LDA, SDF, or RNAV and one precision approach: ILS, GLS, or MLS." There is, therefore, no requirement for the aircraft to be fitted with an ADF receiver or, indeed, for any tracking using a RMI. On the other hand, single-needle tracking both to and from a beacon, as well as single-needle holding procedures, are usually required in a CAA IR Skill Test.
A comparison of test tolerances reveals the following differences, among others:
Departure/Cruise:
FAA - Maintains the applicable airspeed within +/-10 knots; headings within +/-10°; altitude within +/-100 feet; and tracks a course, radial or bearing within ¾ scale deflection of the CDI.
CAA - Take-off/Vr: +5kts/-0kts, Climb: +/-5kts, Heading: +/-5°, Tracking +/-5°
Holding:
FAA - Maintains the airspeed within +/-10 knots; altitude within +/-100 feet; headings within +/-10°; and tracks a selected course, radial or bearing within ¾ scale deflection of the CDI.
CAA - Speed: +/-5kts, Altitude: +/-100ft, Heading: +/-5°, Tracking +/-5°
Intercepting and Tracking Navigational Systems
FAA - Maintains the airspeed within +/-10 knots, altitude within +/-100 feet, and selected headings within +/-5°. Applies proper correction to maintain a course, allowing no more than three-quarter-scale deflection of the CDI or within +/-10° in case of an RMI.
CAA - Speed: +/-5kts, Altitude: +/-100ft, Heading: +/-5°, Tracking +/-5°
Non-precision Approach
FAA - Allows, while on the final approach segment, no more than a three-quarter-scale deflection of the CDI or within 10° in case of an RMI, and maintains airspeed within +/-10 knots of that desired. Maintains the MDA, when reached, within +100 feet, -0 feet to the MAP
CAA - Tracking: +/-5°, Speed: +/-5kts, MDA: +50ft/-0ft
It would appear that the answer to Seaweed Knees' question "Why would an FAA IR rated pilot have difficulty passing a JAA IR test? Especially after the minimum 15 hours extra training that is required" is that, as well as a normal requirement for single-needle NDB tracking, which a FAA rated pilot may never have experienced, almost all of the CAA tolerances are half those of the FAA requirements.
Silverknapper is quite correct in asserting that these posts would have a great deal more credibility if written by someone who had successfully completed the conversion in minimum time having gained FAA qualifications at minimum cost. It may be possible but I, for one, have never heard of it happening.
And, before the allegations start flying, I do hold both JAA and FAA instrument ratings but have no connection whatever with any JAA FTO.