I've tried Gentlemen's Cologne, Keig and Lonach. They were all OK, but I didn't like any of them enough to spend my hard-earned lucre on a full bottle.
My overall impression of Castle Forbes fragrances is that they're simply not distinctive enough to be must-buys.
Gentlemen's Cologne is a fairly traditional-smelling combination of citrus and woods. It's pleasant enough, but I always have problems remembering what it smells like unless I pull out my sample again. That's usually a sign to me that a fragrance is not particularly distinctive.
Keig is a more green/ferny style of men's fragrance with a slightly sour quality when you first apply it. I liked the sourness - and overall I probably liked this the best of the 3 I tried. But Keig didn't have that "wow" factor that often prompts me to buy a fragrance. Again, I felt it lacked distinctiveness.
Lonach - this one is quite sweet. Perhaps too sweet for my nose. I'd describe this as a gourmand-style scent, although I've also seen it described as a "smoky oriental". Personally, I don't detect any smokiness in it, and it's certainly not as spicy as many orientals. I wore this to the office once, but ended up washing it off, because it became too cloying. If you like your fragrances sweet, I think there are many better, more interesting choices around than Lonach.
Overall, I wouldn't put Castle Forbes' fragrances in the same class as Trumper's. I don't find Castle Forbes' stuff as interesting as Trumper's, and they lack that up-market, high quality feel you find in many of Trumper's fragrances.