No, imp cleave works on BONUS cleave damage. Meaning instead of 210 or w/e it is EXTRA dmg, you get 460 or so (rough numbers). if it was +120% TOTAL cleave damage, then noone would ever play arms - fury cleave build would dominate everything :0.
Now the build I came up with - and so far had some testing on (not enough to recommend to anyone, but enough to start a discussion) - is an aoe arms build:
The World of Warcraft Armory
Glyphs of Execute/Cleave/Rending
The key though - its DUAL WIELD arms. You dual wield - FAST axe MH, and fast oh - preferably a sword (thus dual axe/sword spec) for maximum rage gain. Drawback is - you have to get access to the 1handers comparable with your 2h.
So far testing limited to stuff like kologarn is pretty successful - my gear is FAR from optimal and i can get results close to my TG build (aka 11k+ dps)
Why this build works?
First of all, it makes full use of cleave. Compared to TG it has +15.3% cleave damage (TG penalty/2h spec/wrecking crew effects summed up) and +20% cleave critical chance Axe spec adds another 4% damage or so (with the insanely high crit rate - in realms of 80%+ for cleave ) for total of 20% dmg AND 20% crit - or if you prefer around 35% extra damage . Both are huge - and offset lack of Flurry easily. The fact that weapons are fast doesnt actually matter for cleave - since the rage cost is so much lower (counting the MH swing loss), and endless rage. Faster cleave use also nullifies lack of imp cleave. So overall even with lesser weapons and stats on them we do MORE cleave damage.
For single target dps we have execute. Execute that unlike fury version hits really hard (axe spec no tg penalty enrage vs loss of 2h spec) - around 20-25% harder. With a 1.5 speed weapons counting raid buffs, some moderate haste, blood frenzy we are talking about around 4 hits per second - 3 cleave hits and 1 offhand swing. Couple it up with instants, and we talk about 7 attacks every gcd - each having 9% chance of proccing SD. Other gcd are filled with rend/op, and occasional MS - or just regenerating rage. Below 20% you can simply spam execute/cleave with VERY good results.
This is mostly a curiosity build - it doesnt work at all for single target (although some single target arms playstyles MIGHT work with icecrown gear - they seem to scale faster. Too early for me to tell - I personally doubt it, but dont discard possibility that it might work). It excels on fight like anub - with prolonged sub 20% phase, and constant adds - but even then - in my guild we kill adds too fast recently for this build to "work" (as in be competitive with TG). But Ive seen a lot of guilds doing more single target damage, and less add aoe - which propels this build.
However unlike other "curiosity builds" this one is actually somewhat viable, and in certain circumstances, can be a build of choice for Anub, and maybe few other fights.