Hi endlssorrow,
Advantage:
Engage a ID can provide you the consultancy with living lifestyle and design solution,
they can help you to release from the dealing trouble with all the suppliers.
Disadvantage:
Each supplier/contractor might not respond on any faulty on site that involved between the "grey zone".
My advise for u to organized the reno. group as below if you would like to dealing your own:
1) Flooring give to flooring expert to do. (supplier)
2) Kitchen another person to do (contractor, of course, u may separate it unless u r engage the kitchen specialist .)
3) living room + 3 room other person to do (contractor)
4) 2 bathroom another person to do (contractor, stick to one contractor can help for negotiate & reduce the cost.)
5) 3 & 4 can combine togther (contractor)
Feel free to browse my web-site: [remove]
Hope it will help , cheers~!