does the upgrade of the tweeter to 7.0 somehow transform these speakers to the higher end version?No it doesn't -- it just means that the seller has purchased the tweets used in the 7 and adapted them (hopefully) for use on the 5. If these are not adapted to the 5, then it's tricky business (has he adapted the xover?).
Whether it's better, much better, extraordinarily better than the standard 5 I can't say... Cheers