1) Respawn Hell
There are just three outcomes regarding respawning:
a) You are respawned near or even next to most of your mates which of course also applies to the opposing team and most often lead to a sudden death after winning a round when you are suddenly surrounded by most of the respawned opponents (which happens way too often to me, imho).
b) You are the only one respawning in the midst of your enemies. This happens regularly when you just lost the round.
c) You get thawed and respawn on the other side of the map. Sometimes this is good, sometimes not.
The result of a) and b) is utter crap as it leads to a permanent zerg camping/moving behaviour with a lot of spam where everybody blocks or interrupts each other of his own team and each group tries to hold one particular side of the map (most often where the red armor is). It resembles CTF tactics. In order to get rid of this I suggest to start a clean new round with a 1 second down time where everybody is randomly respawned anywhere in the map in order to achieve a more balanced initial position. Furthermore this would solve the (seldomly) issue of beginning a new round frozen when you are getting killed from a shot from the last round some milliseconds after the new round begins. I guess, the item counter should not be resetted - but that should be tested out.
2) Getting punished for being too good
If you are one of the top players of a map, the balance algorithm allocates weaker players to your team and stronger players to the opponent team for the next map. Sometimes this also happens inbetween while playing a map if one team is constantly losing. That, of course, makes it harder for good player to win, which is the reason the algorithm has been implemented.
The downside is that the balance algorithm only affects you if you play one or two maps as the algorithm first needs feedback of your strength. Hereof, I witnessed that some players only play one or two maps or just pause one or two maps inbetween as spectator before they join the game again. While I usually play continuously for several hours, I suffer a huge disadvantage by this balancing like it is implemented now. Therefore I suggest either to use the statistics from here (which would be not so simple, I guess) for balancing teams or - what I would prefer - balance the teams each new round which would also fit to my suggestion on 1).
Statistical side info: Not long ago, I was very good and got many frags over the enemy team which was mostly zerging or camping around. Then suddenly I got re-allocated and not only my stats were ruined but the overall playing experience as it was really frustrating for me playing with such cowards.
3) Pingely pong
As already discussed, only players with a ping of < 100 ms should be allowed to join the server as they seem to use too much capacity and all other players have noticeable connection issues. Furthermore, the unlagged bug of hitting nearly all rails or hitting rails around corners cannot be exploited anymore. I am aware of the fact that this is a serious decision and perhaps it should be considered implementing a soft ping limit depending on the average ping of all players already playing on the server so that high pingers still could play with/against each other.
4) Fasten your seatbelts
This is a short one. Perhaps a CPMA (pro mode) movement variant could enhance the unfreeze experience and if implemented, other and larger maps should be used as well as more rocket ammo

That are my ideas, so far. What do you think?