We've used a number of online gerber viewers to check our work over the last couple of years but one lately has really stood out. That is the one at Mayhew Labs.
Although it won't entirely replace gerber-viewer.com as I kind of get caught up in the spinny roundiness of Mayhew Labs viewer and miss details.
First off dragging and dropping all your layers into the viewer is a welcome change from the search for file, click licence sort of format we've been used to.
The best thing about the Mayhew Labs viewer is you can get an idea of how the layers interact so you can see how your silk screen, solder resist and pads will match up and interplay. Really handy for idiots like my goodself who constantly try new things and get the positive and negative aspect of shapes in KiCad mixed up. In the image above you can see how the solder resist, silkscreen and pads match up.
Give it a try anyway. I'm sure you'll like it!