[maxmsp] dropped noteon messages

Using a Novation Remote SL 25 on a G5 I always get dropped midi noteon / noteoff messages in Max:
- when the SL is connected via USB and
- when more than 3 notes are struck at a time. 

When connecting the SL to the Mac over its MIDI out and a MOTU micro lite USB MIDI interface things are fine. Inspecting the SL's MIDI data over USB using MIDI Monitor.app reveals the Novation is doing 100% ok at all times. There is only Max left in the equation. 

Max patch: notein - print

Anybody's seen this before? 

G5 2x2, OS 10.4.10
Max 4.6.3
Novation SL 25, latest Firmware, connected directly via dedicated USB port, no hubs etc.

Thanks! 

Torsten