Yeah, I guess if LO's become used to swallowing purees they can find biting and chewing quite difficult as they have only learnt to swallow food at that stage. That said, I think if you want to combine the two, if you choose the right foods to give to LO to feed themselves, it wouldn't be too dangerous. Hopefully they will work it out pretty quickly. I have no experience of this, though, so I'm not sure. Tilly finds banana, soft pears, melon, lightly cooked apple wedges, omelette etc. all quite easy to eat. Maybe avoid harder stuff at first if LO has had purees? Someone else might be able to help with this more.
The Gill Rapley books are good on BLW, if a bit repetitive and slightly preachy about the benefits of BLW over TW. I found reading them quite reassuring, though. There are lots of websites on BLW and facebook pages for questions and answers. xx