What's the expected misfire rate with studio strobes?

There really shouldn't be any failures with a pro class system... Some things to think about though:

1. Are you letting the system recharge between shots?
2. Might there be some equipment interfering with the RF trigger signal?
3. Does the transmitter have a problem (assuming you didn't replace it)
4. Is the transmitter within range (probably far less than the spec'd range)

1, 2 and 4 are easily answerable. 3 can be tested by trying different group/frequency settings. Looks like a nice unit though...

I use elinchrom skyport triggers and usually I see misfires after approximately 200-300 shots without recharging the batteries.

I had a similar problem with Bx500Ri's. Every dozen or so times, the head didn't fire. The 'click' of the 12KV trigger voltage could be heard even when the head didn't fire.

In my case, the fault was due to the EHT trigger voltage arcing across to the metal reflector, in preference to ending up on the spiral trigger wire. This was because of a slight, almost invisible, defect in the ceramic pillar that insulates the EHT before it reaches the tube clip. The 12Kv trigger voltage managed to snake across the micro crack in the ceramic insulator far enough to then bridge the several mm gap between the reflector foil and the ceramic pillar.

Short of replacing the ceramic pillar which isn't really an option, the clearance to the grounded foil reflector can be increased several mm by carefully shaving metal off using a sharp heavy duty scalpel knife.