Dear Serge,
I am glad you got to play a Bluthner. I hope the instrument you played was well preped, so that you would not get a false first impression.
The Bluthners I have played are not weak on the bass at all, although I have to readily concede that they were extremely well prepped. My understanding is that they come a bit thin out of the box, but fortunately all the ones I have played had a very present singing warm bass. They are not a roaring piano so if you want to play a lot of Prokofiev you may want to look for a Mason. On the other hand, if Schubert, Brahms or Debussy are on the menu, I find Bluthner very rewarding.
The Bluthner will punish you if you bang it.
Now, your comment on the Irmler, I take exception with. If you played a vertical piano, those are known in America as Breitman, and are an entry-level product (I have also heard about a 164 cm 1/4 cue, but have never played one).
I would be curious to hear from you whether they had what over there I think they call Irmler - Europe, which are made in Poland and come in medium and large (182 cm and 227 or 222 cm, not sure). These Polish pianos can be made to sound very very very nice. I have one (222) and love it (I have been practicing Mozart 415 this week and having lots of fun).
Cheers from across the pond,
H