I haven't heard either speaker, but can't imagine that they would have many if any at all similarities.
stereotypically analyzing(like I said, have not heard either):
1801s would have super detail, tone, smoothness, etc. limited bass(7" woofer), limited(conpared to klipsch) volume, dynanics, efficiency.
klipsch have 100 db(or so I hear) efficiency, huge woofer, HF horn, etc. So, given stereotypes, ultra-dynamics, effortless, fast, etc etc. Also I imagine they need a much larger room to come alive than the 1801s and can probably benefit from some SET amps. possible bright treble, lack of detail, horn glare, etc.
apples to oranges id say.
Also, the 1801s probably would lead to higher end system(and costs!) due to the fact that it can probably show any subtle changes(good or bad) in gear. I read somewhere that the 1801s need a good frontend to really shine, something about spitting back cheap gristle.