To move from the world of "cowboy" Part M maintenance with a small old under-maintained aircraft is surely going to cost a large chunk of the aircraft's value. The only way that could happen is if the CI register issues a C of A without requiring an Export C of A from the UK.
Who, with a £40k PA-28 (yes, I know even that is ridiculous value), is going to cough up maybe £5k to £10k to get an export C of A (A&C, you must know the risks of inviting the CAA to look at an aircraft, gawd know what they might find, especially on a Cessna 172 with all the new SIDs) followed by another chunk to satisfy whatever requirement the CI register imposes to issue a CI C of A.
I think that is a very correct analysis.
And if something goes wrong with the venture then you have to go back again... to face either the UK CAA inspector, or the £1500/day FAA DAR.