I've used DHP a number of times. The only problem I've had is a warning where the aircraft believes there's not enough battery reserves to return to home. This happens on a flight path I've flown many times before, and with 50% battery left. It kinda freaked me out the first time. I normally fly upwind and return on the downwind. The warning only happens when DHP is toggled.
I don't know exactly what data the flight computer is using when it calculates how much current it's going to need to return home, and penetrating upwind surely uses more current than flying downwind. I am a conservative operator and rarely land with less than 20-30% battery shown on the display. I just figured I give ya the heads up on how my flight plan gives me a little comfort.
Fail-safes are great, autonomous and GPS navigation assistance are excellent, but they shouldn't ever be an obstacle for you to control your craft. Practice taking full control of your craft by interrupting a ground station program, putting it in ATTI mode and learn how to regain control during RTH. Do this until it becomes second nature, as if you ever have a control system fail during flight it's a normal reaction, not panic time.
BTW, I've probably 30 flights on mine and never had any control system fail. If one should, and I have an airworthy craft under power, at least I know what steps need to be taken. It's not a 100% guarantee that you'll have a safe landing with all system failures, but it does assure that pilot error was not the issue. Aside from that it's the responsible thing to do!
Being paranoid for others and your crafts safety is a good thing, being prepared for failures is a necessity. Have fun!