The SU7 is, or rather was I think, the flagship Yamaha upright. It has an extremely responsive action when well set up and is certainly a very nice 'large scale manufacturers' piano. How much you like it really depends on the extent to which you like the Yamaha tone.. personally I find that the Yamaha tonal palette is not so broad or distinctive as other pianos you list but then they are not nearly so expensive either.....
Bechstein concert 8's are lovely (again if you like the Bechstein tone) but are ridiculously expensive - considerably in excess of £20k here I believe!!
Steinway uprights are nothing to shout about to my mind and ear and are again very pricey and, if Larry Fine and others are to be believed, somewhat fiddly to obtain a good tuning stability on.
The Steingraeber 130 has a Yamaha action in I believe but is certainly an extremely well crafted, beautiful piano but again costly.... Steingraebers are probably the most 'handbuilt' piano available to buy - they are each truly a labour of love and it shows in the quality of construction. I have played a 138 which was huge and also a 122 which was beautiful.
Grotrian Concertino (is that the 132cm model - i think it is?)I found to have unduly bulky cabinetry... as though it was trying to over-emphasise being a big upright. A good tone, warm and dark but not fuzzy or muddy sounding in the bass, clear in the treble. Nice sounding pianos for sure
Bluthner B - again a beautiful piano with a very distinctive soft and mellow tone... lovely albeit perhaps too soft for my 'uncouth' tastes hehe - but very pricey...costs around £18k here before discounts and anything around £14k is a good price before the New Year increases we will likely see.
I posted some thoughts on a variety of top-grade uprights I encountered on my travels to a new piano in a thread here..... http://www.pianoworld.com/ubb/cgi-bin/ultimatebb.cgi?/topic/1/23314.html#000015
and culminating here.... http://www.pianoworld.com/ubb/ubb/ultimatebb.php?/topic/1/23471.html
hopefully that will help your thinking....
Paul - I got a price on my Sauter M130 not incomparable with the typical prices offered on SU7s and can certainly say that the Sauter knocks the spots of the SU7 in every way conceivable.... if you want a really beautiful and extremely reasonably priced handmade German work of art...go speak to Headingley Pianos in Meanwood, Leeds about their Sauters - truly truly superb instruments
more details on my eventual purchase here: http://www.pianoworld.com/ubb/ubb/ultimatebb.php?/topic/1/24587.html#000017
Happy hunting to you both