Fourth suit forcing

As mentioned in Forcing Raises, I've recently been re-reading Barry Rigal's Test Your Bridge Judgement.  I never knew that fourth-suit-forcing was such a versatile bid until I first read his various scenarios.  Actually, he recommends that if used at the two-level it is forcing for one round only, while if at the 3-level, it's forcing to game.  That makes reasonable sense, although I'm not quite ready to understand the nuances of that treatment.  Forcing to game is certainly the simplest and the easiest on the old ticker!

But what about this sequence, with silent opponents, and playing (or aspiring to play) "expert standard"?

Pass 1♦ 1♥ 1♠ 2♣
In my opinion, 2♣ was clearly the fourth suit and therefore forcing (and not necessarily promising four clubs).  Obviously, it couldn't be forcing to game by a passed hand.  But opener was still completely unlimited and I thought would be keen to know that I had 11 hcp with five hearts (and no enthusiasm to bid 2NT from my side of the table).

Incidentally, with some of my other partners, I play XYZ in this sequence where 2♣ is unambiguously forcing and artificial.  But what of 2♦ by a passed hand (in that context)?  Perhaps that should be natural and, obviously, non-forcing.

In fact, I could make 3NT on 23 hcp and the actual defense (I didn't – shame!).  But my partner clearly thought that 2♣ was natural and raised me to 3♣.

What do you think?