Further thoughts on sacrilege. Fortunately a lot of continental double over and under rifles do have twin triggers - one for each barrel. A double rifle, especially a dangerous game double absolutely needs to be twin triggered. In effect you have two completely different rifles so there is a redundancy. My experience with single triggered over and unders is that its just a matter of time before trigger mechanism gets gunked and fails.

Only downside perhaps of an over and under double rifle, especially a Kirsten locked one is that you have to open them slightly further than a side by side and thus slightly slower to reload. But that is a matter of practice. I have had an AyA Coral for 30 years. This is a double triggered over and under with a Kirsten lock. A couple of times I have been invited on very big driven shoots. The type where most are using double guns with a loader. I was on my own, with just my trusty gun and a bag of shells. I more than held my own. I have been in tricky situations with big animals, but not needed to shoot my way out. I would suggest the best shots will always be the first and then the second. Once familiar with an over and under double, i doubt 3 and 4 would be any slower than 1 and 2.

There is a difference in view down a side by side compared to over and under. Not better, just different.

But by far most important factor is whether the gun fits and does it shoot where you look with you needing to aim. In other words does it shoot like a fine shotgun.