I’ve a dummy which I use to cart both our children around on the school/nursery run, then onto work. I’ve had it about 6 months now and am very happy with it. Like a lot of the reviews mention it does ride just like a normal bike, with the exception you can’t wheelie and it is heavier. Ours is fully kitted out for child carrying with a Yepp seat for the youngest and hooptie, magic carpet and u tubes. The most noticeable thing different between riding a normal bike and this is the weight, not when riding though. Its the side to side weight when mounting/dismounting or manoeuvring on foot, you have to be aware of what your doing or it would be very easy to drop the bike and children in a heap. Size wise I’m 6’2″ on a large. The length is great but if I was any shorter then I’d want a medium for the stand over as its full stand over height, not lower stand over like the modern MTB trend.
I bought a full bike on offer then swapped the surly deck for a xtracycle one capable of direct mounting the yepp seat. The biggest issue here is getting hold of the (xtracycle) parts to convert to full child carrying mode. I was very lucky to find a local dummy rider who no longer used the hooptie so bought that from them second hand. They are like hens teeth otherwise. Similarly the kick stand that comes with the dummy is a joke. If you need to lift the children on or off (which you will assuming seats or a hooptie style device) then you need a proper stand. These are not cheap and the choice pretty much comes down to a) Rolling jackass ($$$$), b) xtracycle kickback3 ($$$ + modification), c) lucky find of xtracycle kickback 1 second hand, d) DIY. All in I think I spent £1600 on the bike then £5-600 on extras!
I didn’t ride any of the alternatives however we have a friend who bought a old yuba mundo to carry their two children on. He has that kitted out with just two seats on the back. There is also another mundo rider local to me that I’ve spoken with a few times who raves about his bike. His children are older so sit direct onto the deck.
If your on facebook there are a few useful groups to look at;
Dummy group: https://www.facebook.com/groups/ILoveMySurlyBigDumy/
UK cargo bikes buy/sell https://www.facebook.com/groups/128645471090212/