Hey!
I recently just purchased a Boston GP-178 PE and I love it! It is beautiful, the upper range is sparkly and the lower range is deep and rich. The action is hea...vy out of the box. Which I happen to like, but that can always be lightened up.
To be perfectly honest, I tried many different brands of pianos and they were all really good. However, I did not like the Estonia... I know that it's a popular "up and comer" so to speak. But, I felt the sound was too "echoey" for my taste. Granted, I only tried one or two.
The Kawai RX's were surprisingly good. I remember trying those pianos out back in the 90's and they were terrible. That company has come a long way. The new action was fantastic.. I felt like I was cheating I could trill so fast. I find, however, that Kawais are hit or miss, some are amazing and some are terrible... don't know, maybe it's just me.
Anyway, I chose the Boston because I got the best deal out of all of them. Which might shock some people as it is inherently more expensive than the other brands.. however, Steinway dealers have been unusually motivated to sell lately (probably because of the economy).. So, it ended working out better for me than the Kawais and Yamahas I was looking at.
Plus, I like the idea of being able to trade up 100% of the purchase price to a Steinway one day. Yes... I'm a Steinway person.
Anyway, Bostons are made at the Kawai factory and having played both of them, I would have to say that I like them both equally. I wasn't a fan of Estonia, but I have a feeling I'm in the minority on that... so you'll have to judge for yourself. Might depend on what kind of music you like to play.. Personally, I like a brighter piano.
One thing I will say, the quality all of the instruments seem to improve dramatically at the 5'10" mark.. if you have the means, I would recommend staying away from anything smaller than that. Some professional techs agree with me on that as well. Of course, room and money are a major factor with that.
If you've got a Kawai RX2 now, then you know a good piano when you hear one. So, I'm sure you'll get a great instrument.
Also, have you considered Yamaha? The C3 is an amazing instrument.
Best of luck to you!