I've tried it too. Note: everyone's anatomy and clothing style/fit is different, so YMMV. I'm not a big guy, and I wear more fitted clothes, because I'm short & it's the only way I look like a grown-up, rather than someone's little brother.
1) The STP device (with or without the packer) is the easiest device I've used for placement, as compared to medicine spoon or nipple style of fitz.
2) Unlike what chakka showed on his video, it does look like an erection on me if I wear just a harness and boxers. My boxers - worn to fit comfortable but not too big - are still loose enough that it doesn't contain the packer against my body. Looks like morning wood. Once I put my pants on, though, if they are reasonably fitted (like my jeans usually are), it doesn't really look like I have an erection, but it is more bulge-y than just having a packer. If I wear it with boxer briefs, it looks normal - it just doesn't move around as much when you walk/move, and it's not particularly comfortable against the body when sitting. It's not worse than a spoon or nipple or anything else though.
3) Earlier in the thread, I asked about my own issue - that my pants crotch/rise below the fly does not have enough room or space for effective use of an STP without pulling my pants part way down. I tried it, but this doesn't solve that problem. My anatomy + my fitted/short rise clothing + gravity = FAIL on any STP device without having to pull pants or jeans partially down. It means urinals are not in my near term future.
I'm glad I have the whiz freedom device to use as an STP in stalls, but for me, it didn't work any better as a packer than anything else I tried before. However, if you are new to STP devices and are looking for a packer one or if you've had spill/placement issues with the current device you have, and you are willing to experiment on underwear options that will be comfortable, I think it's as good as anything else out there, if not better.
