The autopilot programs are in the manual.
Pfft. Manual? MANUAL? I DON'T NEED NO STEENKIN' MANUAL.
I like to (at least theoretically) be able to climb into a craft, punch the engines, and go. I can read the manual during those boring hours in orbit while I'm waiting to align with or intercept something.
The XR series was great for me, since I could do exactly that. It responded to the same inputs as the default DG (since it defaulted to having the APU on,) and it flew more nicely. The autopilot buttons (along with pretty much everything else) were clearly labelled. The help overlay that showed all the key functions in a single page was priceless, and saved even more manual-diving.
By comparison, the DGIV needed a read-through of the manual before I could even think of using half its functions, and then it broke on takeoff multiple times with no feedback on
why it broke (wing stress? Overspeed in the lower atmosphere? Forgot to flip a switch? I still don't know to this day.) Sure, I could've dived into the manual in detail, but that isn't my style. All in all, I
strongly prefer the XR series to the DGIV, especially now that I'm an "experienced" pilot with them.
As for my own ascent profile (just to stick to the thread...) - I tend to level off around 10km, kick on the SCRAMs -and- the mains until the SCRAMs have "lit up" (around Mach 3.5, but specifically when the TSFC gets about halfway down the bar and the SCRAM acceleration is self-sustaining,) and ascend from there. I usually end up with about 60% fuel or so from this technique, depending on how badly I've screwed up.