secur, i had a homebirth 10 wks ago with my 3rd and it was heaven. i would highly recommend it. esp if you have such short labours - who needs the additional stress of having to get to a hospital? i think you should tell them you are having it at home as you are quite sure they would agree thata planned hb is much safer than an accidental one because of v short labour, and go for it! if your kidney has never given you a problem then it isn't about to in labour (if it is stressed by pregnancy that will be apparent before labour) and you've shown that you casn manage short labours w/out bloodloss. planned hb has to be the nicest and safest option for you i'm sure!
and congrats by the way