A little word about this subject. I haved used both of them and both can give more or less contrast or grain, depending of the recipe used. Maybe trix can be more pushable than the hp5. On the other hand, I prefer the no-curly hp5 film and its transparent base, while the trix is curly and has a purple base (anti-halo) that cannot be entirely removed even with a pre-wash.
It's only me.