Hi,
Got an Ultima 390, used it for the last two years and have had problems with rain water pooling on the roof in heavy rain showers. Doesn't do it every time, I think it may depend on how heavy the rain is. As previously mentioned there are bracer bars which go across the awning length wise, the water was pooling above these, between the top one and the van. On the occasions when I did have the problems there had been no obvious sagging or slack in the awning before the rain started. I think it had a lot to do with the amount that was falling plus the run off from the caravan roof. No problem if you are on site, easy to push the section up and allow the water to drain off but if you happen to be off site when it happens I think you could return to a torn awning.