Gotcha, now I understand where you're coming from, and its the same gripe as earlier, namely a lack of scaling. It's a bummer and something I'd like to see implemented.
I've been doing more SpOps matchmaking just to see, and every one of my early matches had lag, sometimes debilitating, but it started to clear up after a while. Not sure if the game just learned that its better to make me host or what ;P
So I know I'm usually more positive on Spartan Ops here, but that's mostly because I play it as a group of two or three a few times a week. Solo or duo we run them on heroic, usually saving legendary for three or four players or when we're feeling the need for some challenge.
I actually have only had one or two somewhat laggy games in SpOps matchmaking. It's been the best out of all Halo games with respect to online co-op. I live in Western Canada, so I imagine that will have something to do with it. I'll play with a couple friends, too, and I don't even get any noticeable input delay, either. It's pretty nice, actually.
I'd love for there to be scaling, though. That was one of the things that bummed me out the most with the Campaign and Spartan Ops initially. Hopefully it'll be something included in future games... but until then, I don't think it's all that playable solo unless you play on lower difficulties. It's beatable, sure, since you have unlimited lives, but playability does not equal "beatability".
Which leads me in to some other hopes I have for the distant future of these kinds of modes, be it Firefight, SpOps, or whatever:
-Greater risk/reward: I want to be able to choose to take a more difficult route through a level, but be rewarded with, say, a nice vehicle or power weapon. The sleeping grunts part from E6 are a good example of this, but do it more.
-Similar to above, but the ability to lose a mission: Why can't I lose? There was only one or two missions I think where that was possible (the generator defense missions). Losing a level doesn't necessarily have to be running out of lives, it could be failure to reach a certain point under par time, or failure to find all the hidden nukes in the Infinity engine room (which could be randomly placed, so as to have a different experience each time).
-Expansion on "competitive" aspects of co-op: That means scoring, but also things like earning multipliers for things like consecutive grunt headshots, multikills, etc. with more immersive systems. Personal Ordnance actually starts to make a ton of sense if you think about how it could be used in a more co-operative perspective. It should contain some sort of visual flair. The music should be leveraged here based on how I'm playing, why not have some of those remixes start pumping up the players if we've been kicking major ass - that doesn't always have to be implied by the design of the level, Halo is a sandbox game, so every attempt to make each playthrough unique is good in my book.
-Team-based "co-op". Reach had that Firefight VS idea - that's cool, expand on that with other gametypes and enemy patterns.
-They talked about tower defense in that making of video: Hell yes. Let me set up custom fortifications in some levels, similar to Horde in Gears 3. Tower defense is addicting as hell, and I think it could work for Halo quite effectively if done right.
-Custom Challenges: What ever happened to those? I like being able to go on Waypoint and make my own Challenges to gain credits or whatever - which also leads into another point...
-Forge "Store". Valve have been doing things like this for a while with user generated content. Obviously, this is dependant on Forge mode being compelling with respect to features, but assuming that, you could do some really interesting things with that network of users. More robust voting and sorting options. I want to see a store front for maps, gametypes, etc. that are voted on by the community and curated by noteworthy community members or employees themselves. Bungie Favourites had the right idea. Credits/XP could be leveraged here as a sort of digital currency to create markets and value. 343 have stated that they want everyone, no matter their interest in certain modes, to be able to progress through the game. My question is, why have it be a linear progression? An economy is cooler. I would like to see Forge tools expanded upon greatly in the future. I should be able to make robust maps, gametypes, etc, but I should also be able to get in there to start scripting my own versions of Invasion, or Firefight, or Spartan Ops-like missions. Halo works best when it's treated as a "platform" for content, in my opinion. I have no doubts that Bungie understood this, and I think that will likely be the direction they head in their future games.
I'm getting too ambitious. Time to tone it down a bit...