I agree with you about tigers in a nutritional sense. They do contain some fatty acids and minerals which are an essential part of a carps diet but otherwise are fairly useless nutritionally (which is why I believe they generally blow quite quickly)
As for your argument that they can cause health damage due to a lack of nutritious absorption, again I agree, only in situations however where tigers make up the greater percentage of a carps diet. I would also like to point out that just about any popular carp bait you can think of : sweetcorn, pellet and of course boilie would present similar problems to a carp if it became the fishes primary foodsource over an extended period of time. Even the best HNV baits do not provide all the nutritional requirements necessary for healthy fish.
As for vent damage I would suggest that this is highly unlikely if using properly prepared tigers. I would go further and also suggest that if I am wrong and tigers do cause vent damage then surely this could just as easily occur with a handful of tigers as it could with 50 handfuls. I would also like to point out that carp in certain waters gorge themselves on snails and sometimes crays. Their vents don’t seem to suffer from a large proportion of sharp shell fragments passing through. Even the odd rock sometimes slides through.
Tigers have a bad reputation from a time when they were totally abused as a bait leading to some necessary and many unnecessary bans.
I don't use tigers often and when I do its generally with bags as I've been fishing for a take. I have used them in larger amounts though and caught a few in one sitting. None of the fish caught in those circumstances suffered any ill effects from being caught in that manner.
If I became aware that any method I was adopting to catch fish was having detrimental effects on my quarry I would cease using said method immediately as my priorities are most definitely in order Ollie
Have a glass on me fella