The films marketed by LDS as parish registers are of the official copy done c.1911 - the actual registers are now on deposit at the Manx Museum and probably will be microfilmed in the near term future - recently I looked at the baptisms in Santon 1700-1760 using the microfilm of the 1911 copy - I found two significant errors
1758 isable Moore not Isable Brew & John Kissack in 1758 (mothers name copied from previous entry) and in 1713 son of Thos and Margaret Christian was Wm not Thos (again a simple mistranscription from an adjacent name)
these were the only significant errors I detected in siome 1000 entries - there were what I call minor misreads of 'i's and 'e's in a few names but on looking at the actual PR these entries were not always 100% clear - obviously I may have missed others but my research involved reconciling burials and wills so I expected to detect other errors.

The moral is that both for Santon and from earlier work on Andreas I have found the 1911 copy to be remarkably good.

The IGI however is a right mess - the handwriting of the 1911 transcription is generally very clear - a uniform modern hand but the transcribers of the IGI have introduced numerous errors