I think 2000 is a good limit. If it were much higher LC/rant whoring and such could become excessive among the top tier players.
Share is a naive solution to an interesting problem.
Share can create very assymetric scenarios, because the top tier players on a team can feed eachother,
as such stacking differences can be amplified.
When assuming the top players will share equally to all share isn't entirely assymetric;
The entire team can benefit from a expert player. If that player decides to camp with a rant or chainsuit and just keeps donating to his team this can lead to very skewed scenarios.
But: unskilled players that feed excessively will indirectly donate that XP to the enemy, so this does balance it somewhat. OTOH that would require a hetrogenous team of high skill and low skill, if the team has a lot of average players that don't feed blindly it would certainly amplify stax.
Another problem with share is it creates a lack of incentive for the low skill players, players not bothering upping their dretch skills and such, just sitting in base and whining for evos/creds

. Again, it's somewhat counterbalanced by the fact that they might get more experience in using the bigger aliens in the long run.
But it doesn't solve the problem on a per-round basis.
A less naive implementation might work better?
For instance, you could view it as some kind of negative income tax
1. high skill players donate XP into a shared team pool, so no cherry picking by the top players
2. these would then be redistributed with following conditions:
2.1. low score/time ratio players should be favoured
2.2. to avoid excess stax; redistribution rate should be dependent on how the team is doing.
"How the team is doing" is an open question, stages and frags/deaths ratio seems a good starting point.
In such a system the low skill players can still feed the other team with the redistributed XP, but the balancing+spreading mechanism would make it less excessive.
You could even make it a tax system instead of a charity, but I imagine then you'll have to deal with a ton of camping and bitching about feeding.