I would go with all of that. My one experience of riding a Brompton was taking a trip on my daughter's (which she inherited from her mum). I probably did a bit more than 20 miles, finishing up on a muddy towpath. Conclusion, it felt like you needed to be in a pin-striped suit going between bus and tube stops. It was too short for me (although daughter and ex both ride/rode much the same size normal bike as me) and I didn't find it very good at going up hill. It was useless in mud off-road.
Then my daughter put the front wheel into a pothole in central Wantage (she was using the Brommie for going between split school sites; the bike sat in the classroom during lessons, much to the amusement of the pupils. This was an ideal use for a Brommie). Result 12 months of agony before someone discovered that she didn't have the sort of injury they were treating her for and that movement was the worst thing to do!
I now have a Montana, which is a cheap italian Tern clone. It doesn't fold quite as small as a Brompton,nor quite as quickly, but it rides very nearly like a real bike. I have built my own extension seatpost which adds a lot to riding comfort, it will go off-road (at least muddy forest trails) and I am modifying a Tern front pannier carrier for more extended use. 80kms no problem and very nearly as quick as my tourer. And you could have three or maybe four for the price of one Brompton.
I have come to the conclusion that most, if not all, folders hit a limit in standard form of about 5'10"-6' which is probably a lot to do with the compromises needed to have an acceptable size folded. Over that size you need to look very carefully at what options (bar design, extended or telescopic seat posts) are available (as well as dedicated luggage options) before choosing your bike. And if you don't need the fold advantages of a Brompton you probably don't need a Brompton.
I know nothing of Moultons, they're a long way outside my price range but I did always fancy an Airnimal (but less adapted for the real use I have for the Montana, which is picking up and dropping off company pool cars; the rest is an enjoyable bonus). Airnimal don't export to my country of residence! I personally wouldn't touch a Brompton, prefer a bike to ride over a bike to carry!