According to what I know about the Scharnhorst´s they were the most succesful single Kriegsmarine vessels. (Both ships destroyed 1 Carrier, 4 Destroyer, 16 merchants and three escorts) While classified as a BC they indeed represented a "anti Battlecruiser" in Fischer´s original conception (speed and firepower for protection). They had a 11 inch armement, which was excellent for it´s gunsize (range 42.000 yrds +, very high muzzle velocity, good deck penetration, good preciseness, cyclic rate of fire: 3.5), but inferior to contemporary gunsizes (except maybe Dunkerque-class) of any BB/BC.
Indeed, while most BB have a small immune zone against 15 inchers they have a very wide against the 11 inchers, and this is a disadvantage battling a BB.
Her protection was better than any other BC ever made (including Hood). Subdivision was excellent. Some says this qualifies it as a battleship. Her belt protection was a little better than those of the Bismarcks (350 mm KC vertical + 105 mm Wh at 45 degrees + 45 mm ww inclined) but without stronger upper belt (only 45 mm), her deck armor was inferior to that of Bismarck. This makes the ship even more immune to point blanc ranges of any thinkable gunsize (up to 20.1") but vulnarable at plunging fire even at medium ranges (vitals could be reached by british 15"/42 as soon as 17.000yrds but more reasonably at 19.000 yrds, what is in within the usual fighting distance). The extensive armor layout contributed a lot to the heavy displacement of the ship. While designed for 32.5 kts both ships recorded less top speed than estimated (Gneisenau 31.8 kts, Scharnhorst 31.6 kts at standart displacement), thanks to it´s higher executed displacement (Attention! The main belt begun at full displacement only 1.5 m above the waterline).
All I know underlines that both ships were very "wet" at heavy seas up to the "A" turret. A plus for the design is their large range, At 30 kts usual speed they could achieve ~4.300 nautic miles without refuel. This should play a role in the Atlantic while facing the slower short legged but more powerful RN hunters. Actually, while not Fisher like, these BC were the only ones, which acted like a BC: They used their superior speed to engage inferior enemies (Glorious, Rawalpindi), dictate the range or disengage BB (Renown, Nelson) any time and strictly stayed out of the battle line (Scharnhorst also tried to disengae DoY but two full torpedo salvos from chasing DD forced her to slow down her speed). However, it´s design was a little flawed: Their protection was optimized for close ranges but they were no close range fighter´s like Bismarck but BC depending on speed and range so a better deck protection (even better than Bismarck) would be more reasonable for these ships, I think.
The Gneisenau refit begun in 1943 could have given the design a better performance at all: refit 9 11 incher by 6 15 inchers would give a better punch, replacing the secondary and tertiary artillery by a single dual purpose 128mm calibre (twin tureet C-42 design) would be better, too. The refit with Würzburg Riese Radar could give the ships a better air search capability and the elongation of the bow contributes a lot to additional lift and a better length-beam relation, thus making the ship more seaworthy and considerably faster with the same powerplant (32.5 kts would be achievable surely at standart displacement) or allowing a better main deck protection at 32 kts.