Wasn't that worried about showing the domain but have edited it anyway. Thanks for the advice - certainly helps to know whether to build it with or without www. as you are correct the domain was exactly as advertised
Usually
http://domain.com is higher TF than domain.com. I think the difference is basically this :-
domain.com = only backlinks to domain.com, the homepage
www.domain.com = only backlinks to
www.domain.com homepage
http://domain.com = all backlinks to domain.com, ie domain.com/, domain.com/some-page
http://www.domain.com = all backlinks to
www.domain.com, ie
www.domain.com/,
www.domain.com/some-page
and yeah, you should always set the site up on which ever version www vs non-www has the most/best backlinks. Usually it's www. In 80% of cases I've found. And of course 301 all your 404 pages to the homepage, so you get maximum link juice to your homepage, where your money links will reside.
As for tech domains, I don't do niche domains since I don't recommend using these for money sites. Not because they would do any damage, but because the boost you'd get wouldn't be worth it. I build 10-30 of these per month for my pbn, so the power of 1 alone for a money site is small.
For money site domains I recommend getting a power-domain that's not expired. I get mine from seodomains.co.
If you're after niche domains for your pbn, then it's not the worst idea in the world, but you severely limit yourself. The content of the previous domain doesn't make much difference. All that matters is the content you put on it after you set it up again. The way to rank with pbns is just playing the volume game and setting up 10-15+ per month and just keep doing that month on month until you stop seeing growth, or the returns become diminishing.
The whole "niche domains" thing is a fad created by sellers who have junk domains, but want to mark up their prices because they're "niche domains".
Even for my money site I don't bother with niche domains. I bought a $700 domain the other day that was previously a book store. I'm using it for a general amazon review site. No book reviews at all, but it has 3k backlinks from 300 RDs, TF28 and almost every backlink is from an authority site like huff, nbc, bbc, 6 .edus etc