At 300 brake both engines are fairly stressfree, but if one blows up it costs peanuts to replace where as with the other one you will need to sell some kidneys, remortgaged the house, speak to the bank manager, etc to get it replaced because you'll simply want to have it with at least 500 bhp as only peasants drive yb poweed cars with anything less

Been there with both and the weight advantage the yb gives over the boa is very significant, at least in the sierra it is.