The short version: Nose down is stupendously easy hyzered or anhyzered. The steeper the angle the easier it gets to have the nose down at least in some earlier part of the flight than with flat shots. Easiest ways to get annied or hyzered nose down flight or even extreme nose down are rolling the wrist or the shoulder and using the Bonopane grip. Flat shots need many more tricks executed properly with proper timing and there is a minimum muscle power requirement to pull it off. And still may be inaccessible for most for high throws with the front being lower than the rear of the disc.
Flat shots missed penalize easily but getting it right also provides benefits. If you have a point and shoot disc for a laser you just smash it to the middle of the fairway or if you're close enough to the side of the basket that the fade brings the disc to the pin. Throwing s-curves in tunnels creates more error sources for thinking and disc selection plus missing out in power generation will wreak havoc with s-curves. Straight tunnels need to be fairly short if you wanna throw over the obstacles annied or hyzered and there's the issue of winds. The short version: One needs to master flat shots, annies, hyzers, s-curves and preferably rollers and overhands at least to be able to manage all courses in all conditions.
Flat shot front and rear of the disc at the same height for 17' apexes to 400' is not a problem once proper mechanics sans perfect wrist extension. And a full disc pivot. Achieving the same with added apex heights is a more complicated matter. Mike has more power than that so he can throw the disc parallel to the ground to a higher apex point at full power. Throwing higher than his power allows and with the front of the disc lower than the rear of the disc needs a lot of things done right that aren't always necessary for hyzers. So a flat shot is the most demanding shot.
If you hyper spin with the wrist never bending left of neutral and snap to the right of neutral you don't need to account for the wrist bones raising the hand during the wrist snap. Like it would happen snapping from hand to the left of wrist neutral to wrist straight. Using the upper muscles of the forearm can be beneficial for forcing the hand to stay down. The more you lean forward the easier it is to throw nose down. The less you raise the arm from reach back to the rip the easier it is to keep the nose down. The harder you pinch and the more the disc pivots the easier it is to get the nose down.
Sometimes tight s-curves can fit within obstacles and then that is a good cheat for getting the nose down more easily than with a flat shot.
Hyzer flips are good for tight tunnels in calm conditions. In windier conditions you need beefier discs that can be released flat and fly without turning and with low fade while handling a fairly good amount of wind. How come i love the newest Beasts? More HSS than anything as little fading and longer than anything less fading.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.