As far as the Colt versus Remington argument goes, only an analysis of the structural designs can answer the question, and not having done so, myself, nor having seen an a force vector analysis, I won't weigh in on which might be stronger. I do know that people seem to shoot either one for a lifetime, it seems.
As far as open top versus top strap design goes, in general structural terms, the top strap design will lend itself to something stringer because you have something retaining the barrel and recoil shield, both, from the top and the bottom. With the open top design, you have something retaining the barrel and recoil shield from only the bottom.
Think of it in terms of picking up an object, while trying to keep it level. It is easier to pick up an object from both sides, while keeping it level, than it is to pick up the object from only one side while keeping it level.