I own mine about 1 1/2 year, and it is my favorite rifle.
Topped it of with a Schmidt & Bender PM II 4-16*40 (kinda overkill).
Mine is a limited edition with a DJV stock. (not made anymore) and a 1 in 12 twist. I shoot PRVI 55 grs FMJ-BT. I only shoot at the range, punching paper. Current production has a 1 in 9 twist so it will shoot heavier bullets better.
Even with this cheap ammo, i get 1 moa standing of a simple bipod.
It shoots great but you have to take into account dat due to the small opening in the action, it is impossible to single load, you have to load via the 3 shot magazine.
Very stable action with 6 lugs and a very smooth 60° bolt throw. The bolt falls very naturally: after the shot you push it up with the upside of the hand (no need to grab the bolt knob, pul back with your fingers, push forward and down with the ball of your tumb: very smooth and fast.
Trigger is a good single stage trigger at 2 pound, this is the only thing I would alter because (strictly range guy) I love a 'pressure point trigger' or dual stage trigger (don't know the proper English term for it)
The other german rifles you mentioned are designed for larger hunting calibres. The 1770 is designed from scratch as a strictly 223 rifle.
As I say it is my favorite. Number two 1909 Swedish Mauser, nr 3 K31 of a total 10 long guns.