Get closer to -current and turn on SCSIVERBOSE and then send me the output- 
I doubt it's an AIC specific issue- it's more likely a tape driver<>Archive
issue. Specifically the 'illegal request' check conditions- I'm wondering
which command caused them agita.

Also- do us a favor and check to make sure you have DC 6150 or better
tape (open the gate on the cartridge- if the tape is dull instead of
shiny, you have QIC-24 tape- and you can't write that on an Archve Viper
drive although you can read it...)