A little trick that I picked up a long time ago. Make another game where you will not be actually playing. Instead bump up your tech to something considerably above your current reasearch (use the all reasearch button) Then you can go in and design systems using the different tech levels and see how much it will cost to reasearch the system. That way you can take a look at which will be faster, to go with current tech, or wait while you reasearch a better tech. For systems with several components, and a size modifier you will often find that new reasearch to start with is much more cost effective than prototyping a huge system. Your jump engines are a good case in point. Another example is for active/passive sensors, particularily actives. If you need a particular range of detection then upping your base tech in the beginning is good. Later in the game it can switch sometimes because of the escallating costs of reasearch.
Hope this helps in the future.
Brian