I have a NiteAngel enclosure and can confirm that it is on the heavier side. I'm very glad I purchased the wheel attachments to move it around easier since we have it on the floor. The lid/ top is sufficiently heavy that I don't think a Syrian could reasonably lift it- at least not the model I have. However, the pegs that connect the top have slipped out once or twice (this is over the course of a few years of ownership, so I haven't considered it a big deal, but it did happen). It was a situation where I think something had just started slipping out over time and then one time I went to open or close it and realized I had to reset it. Ours has slits across the whole top, but no side ventilation, but it hasn't proved a problem. You can see our current set up in the enclosures thread.
