Changing a F4/P3 to a Cr4/P3, worth it?

[Outback]

I only recently discovered the Tome of Battle (well, re-discovered). So now I'm looking at it, Crusader amongst others, and Im thinking how incredibly cool would it be to change my Main party's Fighter levels (first four) into Crusader levels instead? (No seriously, I'm asking!) He's a Paladin for the rest of the way, up until I haven't decided how high yet but lets just say he keeps going a long time. I took the first four levels in Fighter mainly for the added Feats to help him tank.

The build so far:
1-4: Fighter.
5-7: Paladin.

Feats: Power Attack, Dodge, Weapon Focus: Dwarven Waraxe, Shield Specialisation -> Active Shield Defense, Improved Shield Bash (->Agile Shield Fighter at lvl9).

He's the party tank. I want(ed) to build him as a Shield fighter, I think that'd be cool. Blocking and knocking out teeth all over the place. But now that I've read into the Crusader class, I'm having second thoughts. And the worst thing is, I already swapped this guy for my Fighter Barbarian I started out with (yeah, I'm that guy).
Tho technically I wouldn't be changing characters, I still fear a book to the head in in the cards if I suggest this. Therefor, I ask you kind Giants, do you think a swap from Fighter to Crusader could/would be worth it?

Your two cents, please.

[Bluydee]

Definitely, though I don't think you need the paladin levels with it either.

[Flickerdart]

I would recommend Fighter/Crusader, actually. There's too much overlap between Crusader and Paladin that you don't get as much out of it as you otherwise would.

Something rather amusing you could do if you insist on staying Paladin is take From Smite to Song and the Harmonious Knight substitution levels for some Inspire Courage, and then take Song of the White Raven.

[Outback]

Well to be honest, I don't want to change things around too much (and I really do fear that PHB to the head). He'll still be "the paladin" with some Crusader levels but if I remove the whole thing, well see above.

The Crusader seems like a more combat capable Paladin the more I look at him. I'll have a look at those feats Flickerdart.

[Xerlith]

Yeah, a Harmonious Knight Paladin4 (If you can, stack Mystic Fire Knight on top of that)/Crusader 3 sounds good. Well, sounds fun at least. Remember about Song of the Heart (somehow).