Halfway correct and correct, respectively.
Medium lasers are the most "efficient" weapons in the game on a heat:damage:ton:crit combination of ratios. However, they lack severely in the range department (which only gets worse as the timeline progresses), and are terrible at grouping damage. A fast medium laser boat with the sinks to fire them is absolutely going to beat the **** out of the same chassis mounting anything else, but anything faster can effectively outrange it, and anything slower can potentially outdamage it even without the standard medium lasers. The Intro-tech meta is significantly more flexible than "Medium lasers win"
The Timber Wolf (Mad Cat) is indeed an omni. It takes less than half a day of work to move the rear mounted launchers forward, though technically it's not a D config at that point. I'd call it a D+, since it's better in every way.
And honestly speaking, the reason SRM boats don't fly in the tabletop game for the Clans is because of their comparatively terrible range. They exist, though not in huge numbers, but they just can't compete with the longer range energy. In MWO, this is obviously not the case, but I don't think that automatically means the Clans aren't going to be primarily ER and LRM. If anything, the fact that the Clan equipment is so much better than equivalent IS gear means that it might make a comeback. After all, the Clan ER Large reaches out to an excellent 25 hexes on the tabletop, and the IS ER Large doesn't even reach 80% of that. I imagine that Clan LRMs would be significantly less affected by ECM, or something like that.
Now, granted, I don't have the full picture of MWO, since my computer can't handle it. I could very easily be talking out my ass on this. On the other hand, the entire idea of Clan gear is to be absolutely better in every way than IS gear, and I can see that kind of design goal leading to a viable ER/LRM option for Clan equipment. When you can fit an entire Clan LRM-15 with Artemis in the same amount of tonnage as an IS SSRM-6, there's bound to be a little shakeup of the meta.