I have an old Pro model with the canvas type material , the base sleds are the same dimensions as the new scouts and pro , they (pro) come off the side and the scouts come off the back, i don't think there any heavier or lighter(sleds) , my bro-in -law has both new models , I hadn't noticed any difference . If the front doesn't go down all the way , just rock the frame forward(while your inside) , till it sits flat on the ice , it may be because of the retracting pole system , and when you close it the materials bind up , and it shifts , a tweek here and there will do the trick .