I used to use the XT dual control paddly shifters (the ones with XT hydro brakes) with an XTR rapid rise rear mech. Worked well for me in terms of shifting, except when you were hauling hard on the brakes and also needed to shift at the same time. Road levers have the same problem, I guess, but I don't think road riding involves as many panic shifts as MTB, so I've never really had an issue with it on the road.
But the thing that killed it for me was that they took up a bucketload of room on the bars and I used to use pretty narrow (580mm) flat bars in those days. The dual control units were only a couple of centimetres apart and it just looked ugly. But I have to confess that everything worked well - braking and shifting were both spot on and low maintenance, compared to the 9-speed SRAM stuff that I used next.
Gotta say that 785/6 generation 10-speed XT has been a dream for the last few years. So cheap, great quality and close to indestructible (except for the rear mech clutches). When "modern" groupsets are that good, it's hard to get sentimental about the stuff we used to ride "back in the day"...