I'm a Jamo dealer and have been for a few years now. Like all speaker manufacturers, the line has strengths & weaknesses. I really really like a few of their pieces. Products like the R909/907, D6 & D7 THX Ultra systems & the new C 80 series are excellent speakers. However, I am bummed that they discontinued the Dark Apple finish on the C 80 line.
Some of their other product can be a bit underwhelming as well. C 60, the A series of on walls, the Jamo subwoofer line (except for the D6 & D7). These are all just OK, and other companies, I feel, offer better value at their price points.
Currently, Jamo is closing out and changing a good portion of their line & thus are giving breaks to dealers who order those pieces & colors. Please post what you are looking at and the colors and I will tell you if they are being offered at extra discounts. If the people you are dealing with are not telling you that the models or colors are being phased out or not passing at least some of that savings on to you somewhere in your quote.... leave them alone! Do not buy from them. Concealment IS a form of lying.
As far as receivers go, I really love Marantz products. I chose Marantz over Yamaha, Onkyo, Denon, etc. I've dealt in, sold, tried, & used them ALL. My experience has been that Marantz is fabulous accross all price points and offers an excellent sounding product with strong durrablity & warranty. Not a lot of bells & whistles, but a professional installer shouldn't need that to get a great working result. Those can often be a hinderance when setting up a system properly.
That being said, if Yamaha is what they're selling, then listen to their reasoning. It will sound great. As long as you don't have to set it up yourself you will be fine.