My approach, and that of most seasoned reloaders I know, is to seat bullets for AL cartridges to the longest OAL possible that will accomodate chamber fit, magazine fit, and cycles properly. And to be completely honest, I couldn't tell you what OAL I seat to without measuring them, simply because I use the barrel, not a number to determine seating depth. And as to whether XTP's or Gold Dots require a deeper depth to enable chamber or magazine fit, again, this would not mean anything to me, even if they do seat deeper. The only XTP that may present some specific OAL consideration is the 147 gr. XTP. But it still doesn't change anything as to how I determine the proper depth using the barrel as my guide.
Work up procedure isn't any different or require any extra attention to detail. Find the correct OAL for your firearm, use a low end starting charge, and then work the powder charge up, stopping when you've reached what your going for, or pressures have indicated your at maximum.