Inverter: pure or modified sine?

Although this might be a bit of a retorical question, I'd love to have some second opinions in this one:

My auto electrician - who's not the one paying for this - recommends I get a good pure sine wave inverter. I've seen a 600 watt one for AU$450, while a 'good' one can easily be double that.

Or I go for a good quality 1000 watt modified sine wave. I've done my research, I 'think' I understand the difference, the former being same as 'house 220v and the latter pretending to be that but with the current following a more or less 'square' wave, and the more you pay for the mod sine inverter the 'less square' the wave hence the better it is for both the equipment you're running/charging as well as - to a limited degree - the battery it's getting it's 12v current from in the first place.

Now there are plenty of people that report using the mod sines with no problems, but there are also stories of people that have stuffed there digi video camera when charging it from mod sines.

Am I being a cheapskates? Should I just bite the bullet and get a pure sine?

Travelling by car with wife and 2 kids, so there's a laptop, 2 netbooks, video camera and battery chargers for still cameras all dependent on the inverter. No, I don't want to stuff the video camera, and getting Kensington 12 volt supplies for each laptop is expensive too...

Any advice appreciated!