Depends on your race. What happened with us was under first ed pre armeggedon. The 3+ dodge whitestar was simply rarely hit even driving straight into the enemy.
What we saw was a whitestar fleet would whip in to the side of an opponent, destroy a few ships and dodge off the table edge. This ment that in general the whitestars picked up a 1 to 3 exp points depending on what they destroyed before running off. The guy who 'won' got 2 on most ships.
Seems fine, but the guy who won was losing ships, so ended up having ships with no exp. Wash rinse repear a few turns and the ws fleet had 5 to 7 on every ship at the fight, the enemy had 2 or less on most. Start the snow plow effect as you drive to victory through the end of the game.
Part of it was we also had folks actively manipulating their fire to get thresholds with one ship, maybe getting the other threshold with a second ship and then getting the kill with a third. Maxing out the xp gained. Folks preferentially targetting the other guys ships with xp dice to destroy any accumulated stocks.
The idea was build up your own stock of exp heavy ships, then use those to destroy the enemy starting around four or five turns in. As long as you are surviving and getting thresholds you exp stocks stay the same or go up. Losing a battle is no big deal, so go 'farming' for a turn or two if you need to.
It would be harder to accomplish under second, but we saw the issue early and didn't want it to continue.
Second issue is that triple damage weapons can leverage a xp point much better than single damage weapons. Using xp points on an Abbai bimith is not nearly as useful as using one on the triple die beam of the whitestar.
You can also play chicken games with xp dice. Trying to get folks to use them to stop a hit, a crit, the table roll on the crit, the specific effect roll. Holding back as the attacker more often than not and only spending when you need.
So to sum up our issues with the xp dice...
Some races that depended on durable ships likely to get off the table gained more than most. Races that depended on expendable ships lost out (we're looking at you drazi).
Races that could manipulate the damage output better got more xp dice.
Races with damage multiplier weapons got a lot more out of the dice they had than others.
Crits, if one guy has an exp advantage, become dependable ship killers rather than a chance of a good hit. Xp advantages can be manipulated and are very very hard to get out from under.
Ripple