I also think the EF makes sense in principle. However, the disadvantage is that in some cases it can take quite a long time for the money to actually end up in your current account after the shares have been sold.
@WarrenamBuffet The ETF makes no sense for people with TR. You can just leave the money in your account. That's the case with Scalable. At Comdirect, for example, you can transfer the money immediately to your current account.
@Dominik_76 depends on whether you have already exhausted your FSA. Otherwise you will have to pay KeSt on the interest from TR. With Xeon, you can defer the tax by retaining it and get comparatively more out of it.