AGI 511A Preamplifier

I have an AGI 511A with manual, brochure, and reviews. It works perfectly. Additionally, I have both the original faceplate with knobs - excellent condition, and the additional rack size faceplate with another set of new knobs in its original packaging. I bought it mainly for the phone preamp section. I know that the phono section was raved for its slew rate (IAR). Other manufacturers would criticize it because of its high slew rate. Any opinions about how it rates to the new high-end preamps with the faster slew rates?
I had an audiophile friend who owned a 511A. It was OK
in it's day (late 70's) but nothing special. It's not
in the same league as current highend preamps.
I think Sean had one that he modified to good effect.