@Goober: I haven't played retail Silent Threat in years. I don't even remember if I beat it on account of how insane the final mission is.
It really is a rubber-band-on-the-trigger mission. The Hades has 8x the hitpoints of an Orion and you have to destroy it with (for all intents and purposes) a single fighter or bomber, after having already destroyed an Arcadia.
The entire reason ST:R was started was because of that mission - the original plan was to replace that mission and just polish the existing missions.
What's actually a little funny with Freespace 2 is that the ebb and flow is less present from what I can remember. But since FS2 doesn't do anything like in Out of the Dark, Into the Night, didn't need to slow down that much.
FS2, interestingly, takes an entirely different approach that nonetheless accomplishes the same effect. With the switching from squadron to squadron, it's like a bunch of 3- or 4- mission minicampaigns strung together. Also, these minicampaigns alternate between NTF missions and Shivan missions. The conclusion of each minicampaign produces the same sort of satisfaction and contrast without necessarily requiring a change in mission intensity.
(The Vasudan section, being 9 missions long, blurs these distinctions somewhat, but still contains mini-arcs and alternating NTF/Shivan missions. Then the 5-mission Blue Lions minicampaign is an extra-long sprint to the finish.)