I didn't try 150 on the center. After I lowered the output level to like 20%, I should have tried it over, but I didn't. I'm really gunshy with retail installs when crossing over OEM speakers - I'm always worried about them blowing.
I personally thought that the hk mids sounded a little thin, and the tweeters a little more forward, than I like. Now, they sounded pretty good - and for the budget we were working with, I think that leaving them stock and enhancing the sub-bass was a good choice.
But I don't have any doubt that Morel Hybrid Ovation, for instance, have better heft in the midbass and are a little warmer.
The Rainbow 210.25? I think the tweeters are just a little smoother while still having a similar level of detail (I think the Rainbow CAL25 is an amazing tweeter for the money), and the mid is similar. I suspect that some of the harshness or forwardness I hear is the top end of the 4" mid, and there's no low-pass crossover present to help tame that top end. The Rainbow does have a very good passive crossover (better than the new Morel HO 4 II).
But it's worth mentioning that IMO upgrading the speakers requires adding amp channels. The customer is willing to do this in future. However, adding two amp channels AND front speakers and a matching center does kick the price up. I think this is the right approach.
I still wanna hear the Dynaudio 1400 Esotar 4"