I certainly concur with JW411 that ducking under the 3deg approach path is a very big no-no.
To fine-tune this point, if one decides to do so or it is condoned at one's carrier, one must know one's aircraft and the runway.
One never, ever ducks under with a wide body due to gear clearances at the threshold - THAT is a no-no. If one is feeling the need to do so because one has even slight doubts about stopping distances, redo the actual landing distance calculations using all applicable factors in the charts, (which normally do take reverse into consideration, at least on the Boeing).
If it is close, one should not be there in the first place. Don't do the approach, period. How one then resolves that, (divert, different runway, hold), is a PIC decision.
With smaller transports, (B737/A320, etc) one may make a decision to do so if one knows the airport and one's clearances and knows what a displacement of say a half-dot low means in actual height above the threshold, (a dot low at the threshold is a big no-no even though it can be technically done).
In those rare situations where one diverges from SOPs, one must think, "Now is the 30" I have in hand, which I may wish I had, 45" from now..."
There is simply no percentage in hitting a light or worse, just to satisfy your passengers' need to get to their destination. I should think that very few companies these days will question the resulting diversion if that's what it ends up being.
It is not uncommon top be slightly low on the glideslope when crossing the threshold. Used to do it intentionally on the occasional short runway where we were in tight confines in the old days before the aircraft were so closely monitored. On the turboprops, we really used to "dip the PAPI's" close in. I remember one particularly short runway where the PAPIs had you landing halfway down the runway. Unsafe. Still did it in the narrowbody jets at one location that was max landing weight and runway limited weight together. Haven't felt the need to on the widebodies....yet.
Is there really any difference between a smaller jet and a larger jet in the threshold crossing height? As far as I know there is an adjustment in the avionics in order to ensure a similar gear clearance over the threshold.
For example, the Boeing FCTM's have a table for "main gear over threshold" with pilot eye height over threshold/main gear height over the threshold. For the 737-600 the two numbers for a 3.0 degree glide path are 49'/33'. For the 747-400 the numbers are 66'/31'. So being a dot low on either is practically the same reduction in main gear clearance. The real difference between the widebody and the narrowbody is the pilot sitting higher for a given glideslope location.
Who hasn't seen near full scale glideslope deflecton below 100 feet? You might need that extra couple of hundred feet of rollout on a slippery runway that was supposedly "braking action reported as fair/medium".