The only worthwhile armor DLC is the Aegis Pack, which gives you the modular Kestrel armor parts. Each part has awesome bonusses, which are pretty good if you play an Infiltrator character (which on Insanity you should).
Other than that, the other armors and weapons aren't that useful, especially since the only weapon you'll ever need in ME2 is the Widowmaker xD.
If you're more into heavy pistols or assault rifles though, you could give the Firepower Pack a try, since the M-5 Phalanx Heavy Pistol and the M-96 Mattock Heavy Rifle are the best on their category, plus it comes with the Geth Plasma Shotgun, but I never tried that one since I'm not a shotgun guy myself.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
