Well your light gathering power will increase a great deal. If you are just a gazer and not concerned with polar alignment or astrophotography then use a dobs. The EQ mount for a 12.5" will be bulky and large, so maybe a Dobs mount will be better for you. These "hot water tanks" are greatly enjoyed if you don't have to pack them far. Consider storage and maintenance. Slewing the sky on a Dobs is easy if you know the sky well. Less things to go wrong. But....(always a but) some of the heavier Dobsonians bases made of partical board can break if not stored in a dry area. Good Luck!!