Well, I meant making replicas look more like the original. And I often use them to have first stage engines on at launch. And yes, there is a difference in aesthetics. It's a lot easier to get the right shape, though for this I use part clipping. And now with the new layering system part clipping let's you make cool shapes, patterns and custom engines (kind of). Though I admit it can be considered cheating in some cases, cos you basically increase fuel capacity without any significant increase in drag.