thor_gentt,
for the 25 years warranty i think they put some conditions there better check if it's comfortable with before commit cause there is no such 25 yrs to cover everything else they will gone bankrupt. there is not comparable cause one is modular which is IKEA type another type is customs builts/purpose builts. everthing comes to customs builts there is a higher price to pay but if IKEA KC is more expensive then must rethink ur strategy    i'm not saying not worth it but at the end is to see ur own purchasing power, well everyone preferences is differ. ignore me if i'm bulshitting. 
maxguy,
18mm not neccessarily better than 16mm, but if it's thicker it may look stronger maybe it does (this does'nt end). The more important thing have to consider is the material they used to produce the melamine board/chip board !!! where does the board produce? in which country and in which country they fabricate/manufactured the material? are that country wood is comparable with our tropical woods? no way NO WAY. the wood we are using was harder if not hardest, u can said that our malaysia made board is consists of many kind of wood species but it's still harder than the IKEA ones. again ignore me if i'm bullshitting again.
p.s. you may google around to see what Malaysia used in their melamine board...... for sure i was involved in this industry !!!