Faramir's Battlehost is pretty bad, there's nothing useful it does, only costs points.
My best friend used to play all-cav Rohan competitively with great results and is now playing all-cav Gondor, his list is a bit different to this. We worked out that an all-cav force needs to have formations/heroes that can destroy at least 1 formation per turn EACH. It also needs an anti-Monster counters and anti-pikes, while also still being very strong if your opponent gets to charge you first with a Heroic Charge. All that adds up to the following needs in the army:
1. Epic Sacrifice - as many as you can get, in 1500 friend usually uses 2 or 3. It gives you defence against Monsters (sacrificing someone like Deorwine to kill a Troll or a Dragon pays off).
2. Epic Rage and/or Anduril - preferably both because they greatly increase your killing speed. Anduril is the obvious bonus, but you wouldn't pick Epic Rage at first because it drops your Defence to 3 - this is where Epic Sacrifice saves you.
3. Whatever you do, a competitive army requires synergy of its units:
Friend's current list:
Aragorn (for +2 to hit)
Boromir (for 6 Might boosting Gimli's formation, Epic Duels, Epic Strike for more attacks with +1 to wound and Epic Sacrifice)
Gimli (for Rage and Rampage - S7 with +1 to wound kills D5 on 2+ on charge and D7 on 3+, you know what happens when Rampage is on)
Eomer (For Rage)
Deorwine (For Sacrifice)
Elladan (For Epic Defence)
5x Knights with Shield
5x Knights with Shield
5x Knights with Shield
5x Knights with Shield
5x Knights
Fortune: Desperate Heroics (here you can either take Heroics or drop 1 company of Knights and take Palantir, they both have their uses, but priority isn't always necessary)
(You could also take Faramir and Isildur over Boromir, depends on the preference. I like Boromir because of his Mighty Blow especially good vs Monsters and in Duels)
1500, 19 +1 Might, 5 Formations, 6 epics.
What happens:
Aragorn goes with Elladan, so his formation gets D8 front, with Aragorn killing with +3 and Epic Strike, obviously Heroic Combat required.
Gimli goes with Boromir or on his own, Epic Rage gives whole formation S7 and with 30 odd attacks they kill about 20-25 models, then Gimli's company kills another ton with Rampage. Obviously Heroic Combat. Sacrifice not necessary unless you're in real danger, then you'd burn 5 Might from Boromir for extra kills/duel/strike/whatever while sacrificing.
Eomer goes with Deorwine, again Rage kills a ton, in case you're worried, you Sac Deorwine. Heroic Combat please.
Boromir doesn't have to go with Gimli, he can go with his own formation for hero/monster hunting.
Desperate Heroics bring back Might for more combos
Those combos don't fear pikes because even a 3-company pikemen get killed. Epic Strikes add extra dice to your formations with all the bonuses.
The greatest thing is that all those actions work for the whole Fight Phase, therefore Heroic Combats are very very useful. Striking before enemy often means that they won't hurt you very much, but if you think they might, then you put a Sacrificial hero into your formation.
Oh and Gimli has been living for 300 years, so recently when nobody was looking, he learned to ride a horse
Hope that helps