If I had the extra $$$ laying around, LS7 would be a no brainer for me. But that's pretty pricey. The best value in the LSx line right now is a stroked LS2.
Rotus is pretty heavy anyway, but the LS1 is about 430 lbs, including accessories and manifolds. I'd say that's only 100 lbs heavier than an all aluminum 4 banger. The think I like about it, is the power is SMOOOTH, there is never any surge at any speed. Very predictable, and very reliable. Can sit in traffic all day, or be ragged on all day, without too much strain.
And if more power is desired, it can go pretty high with mods.