This post took a long time in coming, but that's just because blog post play-by-plays of a Battletech battle aren't exactly exciting, at least not when you're only covering three or so rounds per week.
The rules integration I was testing out went really well; I like how much flexibility it gave the players, at the cost of making Battletech a little less crunchy (my other option was to make it much more crunchy, but there's a limit to the book-keeping I want to manage). Part-way through, I decide to quit rolling initiative for each NPC combatant and broke them into their lances, rolling initiative on a per-lance basis. The players could still seize initiative whenever appropriate (the lance wasn't treated as an inseparable initiative block), but that change still dramatically improved the speed of play. My current frustration, though, is trying to figure out how I should handle the LAMs; I need to reference Aerotech some more, because it's got some comments on this, but the simple problem is that straight Battletech really doesn't handle aerospace fighters very well. They're introduced in the rules compendium, but only for bombing and strafing operations, not as active battlefield combatants. Most of the integration is actually really straightforward, except for one thing: elevation. See, the rules in Battletech don't seem to consider elevation when calculating ranges. For your average fight, it doesn't matter: a battlemech standing on a hill or a building isn't meaningfully higher than their surrounding terrain. But an aerospace fighter (or a LAM, particularly one in fighter mode) is a different sort of beast. They're screaming around at an elevation that's several times the height of a battlemech at high speeds. I currently calculated the elevation difference and halved it to calculate effective range (strictly speaking, I should be calculating the hypotenuse of the right triangle, which I might do if I decide I want to leverage technology to the task). The halving was important because it meant that not everything was at impossible ranges. But one of the players had picked up their own copy of Aerotech and discovered an interesting note: while in flight, a fighter's energy weapons are treated as having double their normal effective range (this is explained by a superior heat dissipation due to their speed). That would address the range issue reasonably well, so I'll probably be looking at that for the next battle.
The players have (finally) succeeded in their sprawling combat. It lasted a lot longer than a normal fight because, in most cases, the enemies will surrender long before everyone is disabled, but since this was just a simulated combat (well, mostly, as I'll get to later), everybody stayed in the fight the whole time (though a house garrison might have stayed in to the end anyway; depending on when and where they're defending). Partway through the battle, we brought on a new player. How exactly they tracked the other player characters was sort of glossed over, but this new character paid the points to be the owner -- authentic, deed-holding owner -- of the unit's dropship. That was an interesting and unforeseen twist. Of course, since we've got this character just showing up in the middle of a simulated battle, her weapons were live, and there was a bit of pointless drama while the NPCs threatened to pull out and order an airstrike before she integrated her 'mech into the simulation. After a prolonged battle, the players came out ahead, though their group leader got very quickly ganged up on and was knocked out of the fight by the end (though he was finally getting into the tactical side of the fight shortly before he was taken down), and their assault 'mech was pretty close -- he actually managed to survive an "ammunition explosion" (simulated, of course), but it left him pretty wrecked. The LAMs did a generally good job of harassing everyone, and I think on the whole it really worked for getting people thinking more seriously about their tactical options in the wargame side.
After the battle, they met back up at the "ski lodge" -- the Officer's Lounge at the Marik military base -- and celebrated their victory. By the end it had seemed pretty definite, but there was a period of time in there that I thought I'd have the upper hand. They did have an advantage, both in terms of numbers and tonnage over their enemies, and the poor weather conditions probably hurt their opponents slightly more (at one point, the weather went from "snowing" to "severe blizzard," which significantly diminishes the combat effectiveness of the Trebuchets and Hermes II 'mechs that they were facing), but it was still a well-fought battle, and they earned the "Jumping Jack" they won in the wager on the fight. The next session will finally be the planning briefing for the mission on Hyde, which will kick off the meat of the campaign. I'm looking forward to that finally getting underway.