Hi Brian,
Personally I would rather have a cover with four trimmed stamps than no cover at all. My collection has gone through many makeovers over the years and still does. As I find better copies I substitute out the old copies. My original copy of a 'white lines added' 2d blue was trimmed deeply into the design. As a schoolboy I was delighted with my find for a few pennies of my hard earned pocket/paper round money it filled an otherwise blank space for many a year. I still have the stamp even though it has been relegated to sitting in a stock book.
As I understand it the Gibbons Specialist Catalogue has a lot of errors and inconstancies. Although I have not seen a copy (it seems to be out of print at the moment) I can sympathise with SG and the catalogue's editor - it must be a nightmare trying to keep up to date with the subtle changes constantly taking place. I ave had several copies of the specialised catalogues (1,2 & 3) over the years and think they are excellent. However the Deegam Handbook in CD form is the answer for me when it comes to Machins.
Being new to this Machin lark I have been trawling the web for information so you may well know this already but another source of up to date information (in paper form)I found is the The Modern British Philatelic Circle Tons of information for a very modest subscription. Go to
www.mbp-circle.co.uk for more information.
Ralph.