I have not driven a 4-cyl with an LTW flywheel before, but other cars seem to be fine with them (sixes and eights). In most cases it really wakes the engine up, but the engine is far more prone to stalling. I think it really depends on how you drive the car. If you always keep it at low rpms, it won't do much for you.
BTW BMP design makes a nice 9-lbs. flywheel
here that is not only cheaper but also most likely of a better quality.