Not sure I'd go so far as to say you get what you pay for. Pricing is nowhere near that reasonable. Instead I tend to group pianos by action.
In Yamahas you have GHS, GH, and GH3 actions, in ascending order of quality. All GH pianos are better than all GHS pianos, and all GH3 pianos are probably better than all GH pianos.
I don't see a lot of difference between pianos having a particular action, though their prices vary a lot within each group. The P155 has the same GH action as is in the better Arius pianos and is the cheapest piano with that action (along with the CP33). It's nice and piano-like. The lower-end GHS action feels quite inferior, and is in all Yamahas that are cheaper. The GH3 action found in the better clavinovas is mechanically the same as GH so it feels identical, but it has a third sensor, which helps in certain circumstances. The third sensor isn't a huge deal, though. This puts the P155 at the sweet point for price/quality. You get almost all the quality of a clavinova for a small fraction of the price. Just below the P155 is the P95, which has only the quality of the lower-end pianos (both in sound and touch) but at a price somewhat close to that of the P155. It's nowhere near the piano that the P155 is.
Another example: the P155 is a far better piano than the YDP 141, which costs more.
To sum it up, it's not that the P155 is great, it's just that there are just a few levels of piano and little difference in quality within each level. The P155 is the cheapest in its level and therefore a great buy. The cheapest GH3 piano is the CLP 330, I think. So that piano is likely to be a good buy as well.
There is also the high-end NW and NW-stage actions, but from what I've seen they are nothing special. If GH3 is not good enough, the next step is the AvantGrand, which is the best money can buy.
To sum up my advice on Yamaha: only the P155 (or CP33), CLP330, and AvantGrands really make sense from a price/quality point of view.
If you gig, then maybe include the CP50, CP5, and CP1 as well. Alternatively, if you MUST have a console-style piano but don't want to shell out for a clavinova, then the YDP 161 is reasonable.