Prorotype D&RGW C-21 class outside-frame Consolidations (#360 & 361) were reportedly rated at four loaded high-side coal gondolas + a "long" 0500-class caboose on 4% grades. On the Crested Butte branch, there were curves and frequent precipitation on the rails to make for tough pulling uphill. Check the Crystal River book for more back-story on the power of these locomotives. The Bachmann engine has many similarities to the C-21, though it is a scaled-down version. Motor overload issues aside, my preference would be to double or triple the hill with those 16 cars in the interest of more prototypical operation. More fun, anyway.
As for the 4-4-0s, mine will start six coaches on tangent track with no signs of overheating. But any grade really cuts the load capability before slipping occurs. This is prototypical, too. Remember when the E&P Eureka ran on the Silverton Branch a while back? She was maxed out at one Jackson and Sharp coach and one "short" caboose on the steeper sections she attempted.
As for the 4-4-0s, mine will start six coaches on tangent track with no signs of overheating. But any grade really cuts the load capability before slipping occurs. This is prototypical, too. Remember when the E&P Eureka ran on the Silverton Branch a while back? She was maxed out at one Jackson and Sharp coach and one "short" caboose on the steeper sections she attempted.