If you want to add a canopy (with door) for the side door of theTigris, make sure you get the blue (smoke) colour. Also the after sales service from Vango is rubbish. Just warning you!
On the other hand we have never had any problems with Outwell.
Normally I would choose an Outwell over a Vango, but in this instance I wuld go for the Tigris 600 for the following reasons: you can take out the extra bedroom and have more living space; you can get a dedicated extension/porch; I am more convinced by the design of the side porch on the Tigris than I am with that on the Nevada, which can cause problems.