Hi, I'm in a pretty similar situation. SIPA with partial funding and HKS with no funding.
In terms of placement, I have heard and read that there is no difference in placement. In fact, I have heard that there is more SIPA graduates than HKS ones in WB, but this is just anecdotical.
If you only consider placement, academics, etc, it seems that there is little difference. However, HKS is the dream school for many, and all pros / cons seem so little when you put emotional value in something.
If I had a partial scholarship in HKS I would take an acceptable debt and go for it. But with no funding I would have to take a massive debt, and that change things.
Hope it helps.