I very successfully flew myself around Europe IFR in a Mooney 201 for a decade or so a number of years ago. It worked very well for about half the year (when BST applied, roughly). Outside of that, you needed to be much more careful due to icing, and the lower availability of open airports when night closed in.
The Mooney was a pretty good platform for it, if you didn't want to spend the money on a different class of aeroplane. But so far as non de-iced SE a/c go, they tend to be well equipped and they are fast and efficient.
Of course, there's a certain frisson to operating SE non deiced a/c IFR and at night.
That was before the low cost airlines though, which I suspect have changed the comparative economics, if that matters to you.
Paul