I've got one, not towed with it yet end of July will be the first time, did have Vectra Estate before 150 bhp no problems with that ( Coachman VIP 520/4 ) According to the Data it's a perfect match for my set-up.
I've got a vectra 150 bhp, and still has the same specs as the insignia for towing. I tow a bailey pageant provence with no problems, and is a perfect match according to the site on towsure.
I was also looking at the Insignia Elite Nav Tourer, as I currently have the 150 Vectra. I had a feeling that it would be a good tower. However I went for a BMW 320D Tourer Business Edition as the service you get from Vauxhall is diabolical!!