It depends on the quality of the pbn. If you build it for yourself and the sites look like real sites go for it. If you want to buy a service here, forget long term. Just my experience.
In terms of your powerful links yes they are fine, but remember you need way more then just 5 pbn links to rank a site. You need a lot of diversity.I'm going to build it myself, is it okay to use only pbn and web 2.0 backlinks for my micro niche sites? Thanks