I'm a fan of having a rifle and sidearm that both shoot the same cartridge.
I've never bought into that. I want a rifle shooting a rifle cartridge and a handgun shooting...well...10mm. But, to each their own.
My thoughts are that the two guns-one cartridge would be useful in more realistic situations like being stranded while hiking. In a majority of person-on-person shooting incidents (military and self defense both included) almost nothing occurs outside of 100 yards, and very rarely does anything happen outside of 25 yards. In those situations, the pistol with a moderate-hot round like 10mm would be very useful for close-up (less than 2 yards) and an intermediate rifle cartridge would be useful for anything further away given the longer sight radius and better "accuracy".
Basically, I like the pistol caliber rifle because I'm never going to have to shoot another person outside of 25 yards or so, and the longer barrel adds both velocity and sight radius. A rifle round designed to be accurate out past 500 yards will never need to be used to its full potential for self/family defense.
I have to respectfully disagree but first, the topic of the Thureon. I'm not a fan of the sub guns. I would certainly like 10mm over a 9mm for a sub gun platform but preferably with someone else footin' the bill for ammo cost... maybe in an LEA capacity. For the size and weight of the carbine I would rather just stick to a rifle cartidge. Not that the Thureon is huge or heavy but comparable weight carbines of a more powerful cartridge are available. It would certainly have a fun factor to it that would make it a great novelty item to have.
On to the diagreement with a rifle and pistol of the same caliber... There is a distinct loss of versatility with this idea. Sure it might be handy in a ranch environment but handy just means convenient. I prefer to cover bases. Two different calibers can generally do that better. If your going to carry 20lbs of ammo, might as well have more diversity than just the platform.
Given the stranded hiker scenario, why have only a pistol cartidge to do you work? I have no problem engaging man-sized targets out to 50m with a full size pistol but that doesn't mean I would want to. If I had to take game at 50m+, I'm sure I could with a pistol caliber carbine but I would rather do it with a rifle caliber. Better overall ballistics at range.
Sure, most encounters take place at close range based on statistics. The percentages, however, are always skewed by that small percent of extraordinary. It would be thought that a man is better prepared having and not needing than in dire need and not having. If you are carrying a rifle platform, let it be a true rifle. A 10mm on the hip will handle almost everything else. And to think miliary or LEO, hard barrier penetration and the defeat of soft body armor are important advantages should you ever find yourself in that drastic
of a situation.
My opinion, remember, just an opinion... is that if your are carrying a rifle, carbine, whatever platfornm other than a pistol, you should not go 50/50 on versatility by limiting yourself to one caliber. Whatever you didn't
need your tools to do that they were completely capable of would just be a bonus, the oposite could be costly.