I guess that depends on how you regard the Pacer. Me, I always thought they were strange but cool cars. Definitely not a great performer. Sort of in line with everything I've experienced with the d5500 head and controller. It seemed like every lab I've worked at has had a few of these heads, inoperable, half-gutted, lying in boxes. Closed-loop is compelling but only if it works. Aren't they notorious for shutter failures? Sporadic controllers? Bad electronics? Is the d5500 really an improvement of the time-honored chomega ii?
I liked the closed loop - it always worked for me without a problem. All it means is that the mixing box automatically compensates for the gradual changes in your lamp and filters and once in a while you zero out and re-calibrate. I have to say it worked very well for me from '86 when I bought it until the fire department hosed it down last year!:o And I always thought the D5500 was reliable