I don't believe the shape has any effect on the end bearing. The following quote from Tomlinson might also be helpful.
"As a a general rule the allowable working load on an isolated pile driven to virtual refusal (by normal driving equipment) in a dense sand or gravel, consisting predominantly of quartz particles, is given by the allowable load on the pile considered as a structural member rather than by consideration of failure of the supporting soil." Carl Bauer
I understand the reason for various tip shapes has to do with the types of soils and obstacles which are to be penetrated.
It is believed that as the driving proceeds, the soil in the immediate pile tip 'front' is compressed and actually forms a 'rounded tip' in front of the pile end. The shape of this tip probably changes with the density of the soils. A pointed pile tip would probably create a somewhat different soil shape, compared to H-Pile or a flat closed pipe or an open pipe pile.
The amount of driving required to meet the final design resistance will be different for the tip shapes. But the final result is that given equal driving/penetration rates, the actual pile capacity should be essentially equal.
My own experience with pipe and H-Piling tend to support the above.
