Are you planning on loading with smokeless or sticking to black powder only? 45-70 loads seem to fall into a few different groupings: modern rifles with strong actions, lever actions (modern variety), and lastly, black powder only. The first category can take loads that will be suitable for the largest game in North America. 405 grn bullet @ 1900+ in Ruger #1 actions. 500 grn @ 1800+ fps.
I haven't seen any loads for 45-110 that offer any advantage. In fact, they produce less velocity unless you're comparing black powder only loads. I believe the Shiloh Sharps is built to take modern factory load pressures so you can shoot 45-70 smokeless.
Add to that, easier, cheaper, more versatile etc. I think I read somewhere that Shiloh sells more 45-70 than other chamberings something like 10 to 1?
Another way of looking at this....I have a 454 Casull, Ruger Super Redhawk. The 454 has taken just about everything on the planet with the possible exception of mature, trophy WalMart shoppers. The 45-70 is significantly more powerful, especially when fired from a rifle, than the hottest 454 load.
Have you considered perhaps a Ruger #1 in 45-70? They're probably 1/3rd the cost of a Shiloh sharps plus perhaps being one of the strongest actions out there. Another option, maybe a little more money...a Browning or Winchester 1885 in 45-70, the modern versions are strong and accurate. These are the ones manufactured in the 1990's I believe. Load it with black powder or load it with smokeless to factory pressures. NIB I've seen that version asking price $1200 to $1700. Ruger #1s are +/- $1000.
I'm in the market for a 45-something and I've agonized over this issue. Looking at everything, especially since I only have $$ for one of something....45-70 in an action strong enough for factory smokeless loads is my choice. Shilohs are beautiful but then so are Ferrari's, Rolex watches and Wilson 1911s.