as I said above, I was under the impression that 1500 W is 1500 W and costs are similar , apart from the shape of the oil rad and the oil stays warm for longer, so you can turn the oil rad off and it'll stay warm for a while, but the downside to that is that the oil takes a while to warm up ( thus needs to be on longer )
just did a quick search and I still think its a much of muchness
https://www.jackstonehouse.com/blog/...vector-heater/