recommend heavy duty duplex laser

I am looking for recommend from others doing anything similar:
spools generated from rpgle, dds
IPDS (mult barcodes, both sides, some rotated, IPDS was only way to get it to 
work) 
high volume-150,000 pages mth (if rated only 150,000 that's no good)
large spools-800-1,500 pages duplex per spool-printing for long periods.
4 drawer (4 forms) 3 legal, 1 letter, all duplex
legal forms perforated for folding, side strip tear off (pressure glue embed 
form).
up to 40 or 50 lb paper
replace 2 - Lexmark Optra T616's with IBM IPDS cards, ethernet -
have long past point where uptime is less than repair time. 
No problem with Lexmark. Looking for quality production machine.
Color not needed.    
Previous experience with other printers: 
perforated forms over 20lb in duplex kills them.
Prefer 2 units to spead load & backup than single unit. 
Must print daily, very time sensitive documents.

Jim Franz