Loft legs, should I use them to floor my insulated loft?

[Yukster]

I'd like to deck my insulated loft for storage. It is 16 m2. I have two options:
1. lay joists across the existing joists, insulate between them and then lay t&g boards on top
2. Use loft legs e.g., http://www.wickes.co.uk/invt/100412 and deck the loft with these http://www.wickes.co.uk/invt/164516/?source=123_75

The loft legs solution seems more straightforward, but is it any good?

 

[freddiemercurystwin]

The thing is they don't spread the load as effectively.

 

[Yukster]

The thing is they don't spread the load as effectively.

Cheers! Whats the best wood to use for supporting the floor? Something like http://www.builderdepot.co.uk/treated-carcassing-timber-47mm-x-100mm-x-3-0m.html or is it OTT? what loft t&g boards are good for the job? Is this what I should use? http://www.builderdepot.co.uk/timber/sheet-materials/osb/osb-board-11mm-x-2440mm-x-1220mm.html And lastly where is good to get them in London?