My advice is to stay away from these kit with midwf with phase-plug. It's badly designed and airflow trough gap between cone and phaseplug is very noisy. A friend of mine owned that kit and i owned a version without phaseplug (model CS265). This one is much better, but still, it has some very nasty peak at around 2 or 3khz and it could not be completly removed even with custom built xover...only with active xover it is somewhat inaudible. Other than that, tw is very good, and midwf can play really low and loud, it's just that it has limited Xmax (i guest it's around 4mm one way) and cannot play loudly low frequencies.
I now own a combo with Seas L18RNX-P + tw Hertz Space 1 and it's totaly different story, u can guess it's far better.
PS: 650$ is overpriced in every way, where i live, they are selled for about 500$ (US).