@Markus
Perhaps. Providing you are willing to wait hours to get a static grab. And are sufficiently satisfied that any or all of the below are working as intended in the os/browsers you are testing...
--If your page is too deep you won't know what's going on below the fold.
-- Regardless of depth you will not know if dynamic content is functional or useable.
-- You will not know if there is vertical cross-over, horizontal-crossover, float-drop, content shooting out height restricted containers, or a zillion other problematic conditions that can only be tested with font-scaling and testing by setting a high minimum font-size.
--You will not know if the page works in a window greater of smaller than yours unless you know enough to check the right boxes in the first place
-- You will not know if the page is functional for mouseless users.
--You will not know if the link states are working properly
And these above are just for starters.
Solutions?
Never, ever, trust static screen grabs much less deploy a clients site based on thinking bcause it looks ok in a grab that it will actually work in the intended os/browser.
Always ask an experienced and well seasoned operator to check your work cross-browser, long, long before even thinking about deploying it. One way to do this is to post for a cross-browser site review.
It is a given, when posting publicly, on any public forum or list that you are open to frank and honest opinion, or downright nasty intentional hostility. Each of us is in the position to know and separate the wheat from the shaft-- to pick the good from the bad, and to come up perhaps a better and more knowledageble designer and developer.