I'm not able to remember all the details, but I think you must always at least get Bronze or the game ends.

I had already anticipated as much.... because it happens with some missions already in Fantasy Wars, and since Elven Legacy is designed to be a harder game, i had already imagined how unlikely it would be that the developers would miss cutting off that loophole.

So which missions in E.L lean more towards having a more useless enough reward that it would be worth doing the bronze victory just to gain a bit more experience?

Or a so impossible that you could not get the good reward anyway, then you may as well do a bronze victory and get more experience?

After carefully studying the rewards for missions, here is a list and my recommended victory target;
1) Meeting Gold
2) Persuit Dammed Gold
3) Master and apprentice just win
4) Wrath Silver
5) Remnants of the Horde Gold
6) Path of Ugraum Just win
7) Power of Durenhalle Gold
8) Sullen Mountains Gold
9) King Victor Just win
10) Amulet of Hexers Bronze
11) Snow Valley Gold
12) Dwarnrock's Order Just win
13) Inquisition Caches Silver or Bronze
14) Harvest (Kill) Silver or Bronze
15) Harvest (Villages) Silver or Bronze
16) High Priest Wont see it, no great loss
17) Barrier Just win

There are a few more i would have liked to nerf the gold victory but they have to connect it to a bonus mission, only HIGH Priest bonus mission seems to have a less interesting looking loot that i can pass on it. And i don't need more flying units, hence the bronze victory for Amulet of Hexers.

Thoughts?

Sorry, I'm not much of a help on this, as it's too long ago to give a qualified advice.

I used to play like this, but now I think it is generally best to go for xp in the first few missions regardless of the reward. Even the best items only improve one unit by a few %, while having your entire army a level higher will be a much much bigger bost. Every level of one unit is like one of the best items. This is especially true in Elven Legacy where the units have much higher base stats.
This also means that after these few missions you will have no problem getting gold AND the entire maps cleared on hard.