I am new to London City and have so far only arrived in the (Level D) simulator. The stable, speed-controlled approach 'usually' results in landing somewhat longer than desired because the steep-approach 'picture' is different than 99% of the places that we usually land. Therefore the tendency is to hold it off with a more aggressive flare and prolong the flare rather than plant it and so the useful runway rapidly disappears under you and you land long. The 'technique' that seems to allow more consistent arrivals (not equipped with a "legal" AOA gauge) is to do as described above, slightly duck under the glide slope and using the PAPI, land on the leetle triangles. So far, this 'technique' has resulted in more consistent arrivals and more closely approximates how I used to do STOL landings in a Dash7 (which was designed for London City - or was London City designed for the Dash?). The caveat is that an even steeper approach requires an even more determined flare (increased kinetic energy to dissipate) and therefore a higher opportunity to pooch it and alarm the passengers.
Anyway, ducking under is a technique, not a procedure and it is up to you to determine if your operation permits such things and whether or not it is even legal. Maybe you need to decide if you should even be there in your mega-jet?
If manufacturers would just add a useful AOA gauge when they certify for higher approaches (or just buy the HUD - go ahead, you know you need it) then that would make for better consistent steep approaches.
Edited to add - if in doubt, there is always ".....Go around check thrust flaps 20 positive rate gear up....."