I'm going to hold off on speakers for now, sticking with my current ones until I get used to my new stylus. I upgraded the cartridge on my TT yesterday from the pre-installed Sumiko Pearl (good cartridge really.) I thought it was just a little too laid back for me and had odd interactions with the rest of my equipment. It would probably do really well with a system that was more forward or bright than mine, and if I had a system like that to try it with I'd have liked to hear the difference.
Anyway, after a lot of reading I went for the Ortofon 2M Blue, and I'm really happy with my choice. Installing it was a pretty easy affair, the head shell area on the RPM 1.3 has a little overhang but I couldn't physically move the cartridge any further up and still align it properly, so it is what it is and I'll live with it. Like the reviews say it's a little stiff at first - definitely a good idea to break it in for 10 hours or so before you start gaining an appreciation for the depths it can plumb and how nimble it can really be. I've heard it described as analytical by some (and not in a positive sense) - I'd guess they'd been listening on a solid state amp or something "bright", but with the SLI-80/V90-LPS combo on the RPM 1.3 it feels natural, deep and the staging is superlative. I'm running Imogen Heap's latest on my HD800s now and the sense of space is immense - cavernous on some tracks. The other day, I was playing a little bit of FKA Twigs LP1 on it and man can this thing dig deep and stay on track too.
So to sum it up, this cartridge gets along well with the Cary SLI-80 very well in my opinion, and if you're on a budget it's worth checking out.
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TL;DR - here's a picture of a Ortofon 2M Blue. It is mounted on a Pro-Ject RPM 1.3 which is connected to a Musical Fidelity V90-LPS which is turn connected to a Cary SLI-80. It's a good match for the SLI-80 and the rest of the equipment in the chain. I would recommend it highly if you want a really good MM cartridge for under $200. The stuff you read on the internet about the break-in period is true, but most of the complaining about how it sounds fresh out of the box are both hyperbolic and silly. I would still give it 10-20 hours before it starts showing you how good it really is, but hang in there because the end result is worth it.