I havent read all of this thread, cuz its sooo flipping long! All I know is, I weaned at 4 months and I have absolutely no regrets!
My baby is now 6 and a half months old, chomping mostly finger foods only now, and occasionally is spoonfed the odd meal or fromage frais. I didn't BLW soley, I have no issue with BLW, and I guess to some degree it was kinda incorperated into her feeding routine since she feeds herself now, and that started at 5 and a half months.
She has whole sandwiches (crusts off) all sorts of fruits and veg and I believe she is good at dealing with swallowing lumps etc due to being used to having her solids from 4 months, then again she could have dealt with lumps perfectly even without weaning at 4 months. Who knows! All I know is, my baby was losing weight, despite having 5 lots of 9 oz milk a day, and it was the HV that suggested weaning.
We havent looked back since.
EDIT-
It is difficult, being a first time mom and that and being told by the HV what is 'best', I didn't know any better so I did what she suggested. Maybe a lame reason to do it, but I wanted what was best for my baby, and to see her dropping several oz over each week, I wasn't prepared to watch that happen. You trust your HV and think they know best, and I am glad I took her advice.