There is no scope "vs" irons, its only scope "with" irons. Its not one against the other!
Below is from shooters eye perspective:
When using iron sights, the eye has three points of focus: back sight, front sight, target.
Since shooters eye can not focus on three focal points at same time, proper way is to focus on front sight (to see clear), while the other two are blur. Thus, the errors occurs.
When using peep sights - there are two points of focus, front sight and target, because we peep, or look through the back sight, which is better design, providing less chances for optical errors, due to eye focus.
Finally:
When looking through the scope, it is all two dimensional picture, and eye focuses only on that picture, without blurred areas during aiming. Thus the eye error is eliminated.
So, theoretically - the scope has almost all the advantages, in minimizing the eye error, plus optional better range estimate via various reticule features.
The scope has, however following practical disadvantages:
Using in heavy rain, heavy snow and blizzard conditions, and liability to mechanical failures with hard handling, accidental hitting in near by objects, car run overs if that happens, etc you name it
Secondly, on close ranges, when quick acquisition of moving target is required, the iron sights are way to go.
So, for any kind of hunting rifle, in my view - it has to be equipped with iron sights, scope and quick release mounts.
While many hunting rifles today do not have iron sights, still I can not find a single reason why hunting rifle should not / could not have both.
Another part is stock - which will define primary and secondary sighting / aiming system.
The shape of stock must enable shooter to naturally align the eye with sighting system (either scope or irons).
Logically, if the eye is naturally aligned with scope, it will not be naturally aligned with iron sights.
So, obviously - one system will be the main target acquisition system while the other will be back up.
Or, possibly adjustable stock to be considered.
One example:
Some newer rifles are equipped with battue mechanical sights. This sights are designed for quick acquisition of targets at close ranges.
I would say in that kind of rifle the mechanical sights would be primary, and scope would be the secondary aiming system.
SO, practically in this example, the stock will have to enable shooters eye to be naturally aligned with mechanical sighs, and when aiming through the scope, the neck will be stretched a bit.
Considerations for: Close range, medium range, long range, moving targets, steady targets, bush, plane, etc...
The main purpose of the rifle will have to be considered when choosing the type of stock- - as this will determine the primary sighting system depending of condition and type of hunt for which the rifle is intended, but in any case - both type of sights to be fitted!