I worked with the Mossberg Patrol earlier this year.
I worked with the CZ 527 several years ago & happen to have five loaner CZ boltguns here now for a project, one of which is a 527.
I made the mistake the first time around of not hanging onto the 527 back then.
I won't make that mistake again on this one.
The Mossberg was quite capable of holding tight groups at 100 yards, the best I got out of it was a 1-incher with one load, using the supplied scope.
Feeding was rough with a couple of the loads, the ramp had some noticeable machine marks.
That could be fixed & was not necessarily a universal problem on the guns.
The length was handy, it feels solid, the flash hider is not a bad idea, the sights were adequate.
The stock is wood under a surface "paint".
The trigger was decent, but I don't personally like that "Glock-ish" trigger on a rifle.
Altogether the Patrol version is a good package in a very handy form.
The ability to use any standard AR15-type mag is a very real bonus, if capacity is important.
As a cruiser gun for LE, it has definite utility for police in a general-purpose role (perimeter stand-off, hostage, barricade, etc.) in areas where an evil black semi-auto may not be approved by higher-ups, for whatever reason.
The CZ 527, on the other hand, is much nicer in finish & execution, has a much smoother bolt, a proven Mauser action, strong square-bridge integral scope bases, a set-trigger (with no Glock two-trigger secondary paddle
), hammer-forged barrel, a very sturdy steel mag, and readily available small parts to keep it going at home if you need to.
I personally dislike a long detachable mag in a boltgun.
It gets in the way of carry, sticking way out at the natural balance point.
The CZ's mag is only a minor annoyance there, the larger mag in the Mossberg is much more of an issue, for me.
Only one serious "can't live with it" on the 527, and that's the tiny front bead sight.
NECG makes better ones & I'm working on replacements.
Can't hardly find the CZ white dots in the rear notches.
If you'll be mounting glass, that's not an issue for you.
You're obviously not looking for a "combat" or defensive weapon, if you're going to let the AR go, so I don't see the hi-cap mag as being that much of an advantage.
I wouldn't like it for field carry, but that's just me.
Denis