When I was on PerC, I found I didn't have a whole lot in common with most of the other ISTJs, though people did compare me to some. I'm good friends with [MENTION=4353]MBTI Enthusiast[/MENTION] still, she's an ISTJ and a 9w1. I have a 9 fix, and I'm a reasonably healthy six, so I guess that could be part of it, too. We relate a bit when we talk, which admittedly isn't that often, and is only online. Her boyfriend is an ISTJ with almost the same tritype as me too, and there are things about him, from his posts on PerC, that I relate to as well.
You're asking in person, which makes more sense of course... I have connected rather well with the female ISFJs I've known in real life. I think my ex-wife may have been ISFJ (she tentatively considered herself INFJ, but knows almost nothing of typology aside from the results of her test). She's a 4w3, without question. I've never known anyone who better fits that enneagram type. I didn't see much of myself in her at all, I guess. We had fun anyway. I had an ISFJ friend for a little while a couple of years ago who I got along with OK but we didn't hang out much. I forget her type, she's on PerC but I can't look at her type since I was banned. The ex-girlfriend I had before my ex-wife I also believe to be ISFJ, and she and I got along very well too. I could see a lot of myself in her, we related very well while we were together.
I don't think I've been compared to other people in person. Online I get compared to a few other sixes and a few nines. There was a thread over on PerC asking what members certain members remind you of, and there were a few mentioned there. I'm sure some were Si-dom.
Sorry I don't have many IRL answers for you. Curse of the cave bear. ʕ•ᴥ•ʔ