I don't think the Reapers behave like the clans, necessarily, but I'm sure they're confident enough of their own superiority to come off as aloof in regards to tactical matters. Now granted, if they don't keep an orbital vanguard of any type or camp the Relays of systems they happen to be invading, then thats just stupid. But in regards to the way they act in combat or their seeming willingness, from our perspective, to throw themselves into unnecessary danger, keep in mind that as far as we know, in the entire history if this happening, TWO Reapers have gone down. One was Sovereign, who went stupid at a critical moment, and the other got hit with what was likely a Death Star sized Mass Accelerator, something that I'm fairly confident no one is packing this cycle. I'd say Reaper confidence is justified.
We should also keep in mind that the Reapers kinda had their plan screwed up this time, and likely didn't have an "Uber Awesome Space Baddie" follow up gambit just in case the organics had slightly better defenses and foresight than they intended. Still kinda lame, but IMO plausible.