Having just skipped through all the above I find it difficult to agree with how 'annealing crack' is being defined.
Whilst it may be that there are cracks in Monart are due to poor annealing, it seems to me that any cracks that occur after production should not be referred to as annealing cracks. If travelling an item to retailer meant that an inherent fault in that item was revealed then it is more than likely it is was as result of that poor annealing - as may also be the case when something is impacted at a later date - however, it is a fine line as to what caused the damage. Without the vibration, or the impact, either item might have stayed in perfect condition.
There is a problem in accepting all cracks as either original annealing cracks, or, as linked to poor annealing, since it means that any crack could be passed off as 'original'. If we accept that original annealing cracks do not grow (which I fundamentally disagree with) then this would also give the unscupulous licence to sell under a false banner.
I agree that the value of a damaged item is in the eye of the beholder, however my experience as a dealer in Monart is that buyers are always put off by any damage, whether perceived as original, or more obviously from later treatment.
My advice to collectors has always been to buy if you like the item and if you don't hope for an increase in value. My advice to investors, or collector's with an eye for investment is, do not buy damaged items - however that damage may have occured. Experience of re-sale on damaged items - especially at auction - is that such items do not do well. Of course there are always exceptions, but as a rule-of-thumb, this statement is true.
I own damaged items because I get enjoyment from them aesthetically and/or because they are rare. Luckily, most display in such a way as to avoid the damage!
I have, in the past taken cracked Monart to restorers. None have come up with a fulproof way of repairing cracks (or in other glass for that matter), which is why as a dealer I avoid damage, but as a collector I may entertain it. I am amazed at the idea of drilling holes into Monart. Might not the vibration, or any heat induced by the drilling, actually make the crack grow? With the imperfections and inherent stresses in the glass might not the crack even bypass the holes drilled successfully by the restorer? The concept sounds somewhat Heath-Robinson, not to say drastic, to me. Does it adhere to Museum practice? If not, it may well be one to be avoided. Perhaps taking rudimentary care of storage and display (as you suggest Frank) might be a better course of action.