g,day Rastis,
I am the proud owner of an 120mm (4.7") Refractor (Skywatcher) and I think its beaut. For really faint stuff I use my 250mm Dob. But my refractor is my most used scope. In deep sky it excells with nebulae because unlike a reflector (or SCT) It has no central obstruction so the contrast is significantly higher. It is also very good for double stars, planets and other deep sky objects too.
Any refracting telescope can be used as a terrestrial scope as long as it has an inverting prism attached.
I hope this helps cobber.