I'm also interested in the answers here -- I asked a similar question earlier in the year & I believe people thought that Model Power locos were pretty good.
I'm also interested in their other stock as well. I bought a 1950s CNR caboose which I think is good quality. However, I recently saw a batch of CNR passenger coaches for sale which made me wince.
Instead of having the dark green that they should have had, the green was a sickly yellowish -- I couldn't believe how "off" it was.
So my impression is, while MP products might be economical, their accuracy and possibly their quality may be hit and miss.
Still curious to hear what others say though.
Cheers, Rob