Haven't read all the replies, but I have twins so never knew life with just 1 child so can't really compare. All I can say is that when I do have 1, it is so much easier.
I don't think the logistics of having 2 is much more difficult - OK, there are 2 of everything to sort - washing, food, bathtime, bag for nursery etc etc - all of that is time consuming and physically hard work but I'm sure most people would expect that when having a 2nd child.
The 2 things that are INCREDIBLY HARD in my view are :
- The juggling - pulled in 2 directions - you want to spend time reading to A but B needs their bottom wiping, or B needs help with his homework and A has trapped her hand in the door. B needs to be at football by 5.30pm, A needs to be at dancing at 5.45pm 5 miles down the road. With twins, at least they're the same age, if they're the same sex, even better from a logistical point of view, but with different ages and different interests etc, thats quite hard.
- The bickering / refereeing - Oh my god - it is just emotionally exhausting with the "he took my pen", "I had the toothpaste first", "he sat in the seat behind daddy last time, its my turn". I can now sometimes tune it out (my twins are 8 and I keep explaining they are old enough to sort it out themselves) but thats the hardest thing in my view about having more than 1.
But having said that, the giggling, seeing them play together, going upstairs to find they've got in the same bed, the shared secrets / experiences, the companion they'll have through life are all priceless in my view. Its definitely a decision not to be taken lightly, if you only want one and fear how you'll cope, it might not be wise to have another because it is overwhelming some days. But there again, at least you'd be going into it being realistic about how hard it will be. Good luck whatever you decide.