I'm going to Canada in a few weeks and am looking to reduce the weight of what I take abroad. To this end, I've been looking at these two lenses - Nikon 18-200mm f/3.5-5.6G IF-ED AF-S VR DX, and Tamron AF 18-270mm f/3.5-6.3 Di II VC LD, and wondered if any folk on here had practical experience of either of these lenses.