the WHO paper says that solid foods should be complementary until one, that's where the 'food is fun until they're one' thing has come from i presume. it's not a blw thing, i was told it at a highly pureetastic Sally Army weaning talk.
complementary does mean that you want them to eat something, however, in those later 6 months. most do, easily, and if they don't, crack open the spoons, who cares, don't get your knickers in a twist about it. plus, the iron doesn't switch off like a tap, it falls over time.
this is from kellymom, and worth a read. www.kellymom.com/nutrition/vitamins/iron.html
"In Conclusion...
My interpretation of this information is that there is no problem with (and lots of advantages to) continuing with exclusive breastfeeding until your baby is truly ready for solids. At some point toward the end of the first year, your baby will gradually begin to need more iron than that provided by breastmilk alone, so offer your baby foods naturally rich in iron and vitamin C as he begins to eat solids. If there is any question of anemia, get a blood test - if baby's hemoglobin levels are OK then there is no reason for additional iron in the diet. "
you'll not find much research into BLW, nor will you find any into purees. however you could say 'well, look at all of us, we're all fine and we were all fed on purees', and so long as you believe that we as a population are all healthy and well then that's fine.
personally i'd say give it a try, if it suits you and your child then you'll know soon enough. some people love it because they find the mess etc less stressful than making purees, some people won't like it because they'd feel more comfortable having some control over what's goiing 'in'. it's horses for courses.