It is, no doubt. But I didn't go for realism really, I'd say this is more of a "convenience" mod. I guess if you'd like to make it more restrictive you could always lower the max distance between vessels, so they pretty much have to be right beside each other to make a transfer. I could add some more restrictions, but leaving some flexibility allows users to come up with very interesting stuff (in fact the first thing I did was to throw "barrels" with fuel around and refuel an aicraft as I skim at top speed right above them, which is ridiculous but really fun! At first I thought about drawing *something* between the vessels so the tranfer process would be more graphic, but when I settled on the transfer method and rates I prioritized quickness (it takes ~3 secs at most, depending on the vessels) so I held back on the idea. I *could* lengthen the transfer process to make it worth adding some graphics, I'll see what the overall response is. About the kerbal requirement, it's a great idea! I can easily add that to the mod, with a config option for those who want it. Next version will totally have it Exactly! In fact, the reason why I created the plugin in the first place is that I came back to KSP after a while and found out cleverbobcat.dll containing Merlin's resource transfer was long unmaintained (and boy was it quirky when it worked)... So I just created something that would fill that need, but 'smaller'.