iainpoll
If there's no undershoot (which there never is where I fly), the technique is identical.
I fly the approach at a power setting which is approx mid-way between idle and full power (i.e. round about 1700rpm in the aircraft I normally fly). That gives the most options for adjusting the approach path up or down. If I'm getting a bit low, and am heading for where the undershoot area would be if there was one, I've got plenty of power in hand to sort things out. In the same situation with a slow, flat approach I would already have a high power setting so I would risk not making it to the runway.
I don't often fly into flat strips that have trees or obstacles on the approach, and obviously your options are a bit limited. If it's feasible to go around (which it isn't usually, where I fly) I would steepen the approach path with a lower power setting and sideslip if necessary. What I definitely wouldn't do is come in "low and slow" over the trees in a flattish approach.
Bar shaker
Obviously it's stupid to create needless risk. The main thing is precision. If you can always land at the intersection, in different wind conditions, and know how you did it - then landing on the numbers is not going to be an issue if you need to do it.
However, if you always land at the intersection when really you were intending to land on the numbers.... then you won't be able to fly into short strips.