OP here... Many thanks to all. Extremely useful! I think we are okay to at least 'test the waters' with my current set-up (no one seems to think the bike will just crumple and fall apart under the weight - which was my main worry)... And now I have wealth of new info on both cargo bikes and WeeHoo's, etc. Both will be very likely candidates in the next year or so...

Just on the point of safety, I found that useful also. He clearly has further to fell from a seat, but will be wearing a helmet and I will be going slowly... At least for now, I'd like him close to me, in easy talking and touching distance, rather than out behind me. Data-aside, I *feel* he is more vulnerable out there and so low down.

I have also read that exposure to emissions is FAR worse at lower levels, i.e. exhaust height (for obvious reasons), so having him quite a bit higher is also much safer/healthier in that regard.

Thanks again, Josh