There is no question, studs are always better than bolts, but do you really need them? For NA and Turbo running stock bust, there is really no need for studs, except the let you align gaskets much easier. Now if you are going to have extreme busts levels then you will need the studs. For rotary, bolts should be enough. For comparo, in diesel world on my truck 40PSI bust is a everyday occurrence, and we are running bolts. anything above 45PSI should be changed to studs. As you can see rotary has a long way to go....
Also, it is not as easy as removing bolts and putting studs in. You have to make sure all your holes are bottom tapped and cleaned, only then you will get your moneys worth from the studs.