I tried the 128,128,128 method and the result is much better, although there remains a slight red-shift which is bothersome, but may or may not affect the final output to a great degree (I have to make some prints to be sure).
I forwarded my same concerns to Lacie and got this surprising response:
“I apologize for the frustration with this but I am going to be up front- the 324 is not a good choice for a proofing system display. The lack of uniformity in areas of the the display surface you describe, in your case resulting in some red shift which you can see, is very probably the result of the the panel technology. The display has a 10bit gamma correction processor, which is actually the weakest of the ones we sell.”
I was advised to buy a more expensive model, the 526. I think Lacie’s response is admirably honest, but also disappointing; I don’t see how Lacie can send this then advertise the 324 on their site as being made for photo professionals and color accuracy.