The lower poly model won't print significantly faster, but it will add significant sanding and finishing time.
Lower the print time with a lower infill or a larger layer height and smooth the mesh before printing.
If you are planning on sanding the model you shouldn't use XTC, it's more for clear-coating and leaving a beautiful smooth surface. But sanding defeats the purpose. You could use any cheaper resin, bondo or rondo combination.
What printer are you using for this print?