A semi dry transfer is not much reliable if you are using the blots for quantification, as complete transfer of high mw proteins could be an issue. If you want to use the blots for qualitative analysis, or just to detect the presence or absence of a particular protein, then trans blot can be a great time saver.
I have used it myself and my experience is really good with the system. try to buy the consumables as well... they are really of great quality.