I'm at about 750 miles total on mine so far, and I'm just averaging a faster speed over a 43km loop of rolling hills compared to on an upright. A lot of this is down to superior descending (the bike has much better stability and braking than an upright, so the reduced fear factor is a much greater advantage than the improvement in aerodynamics), though. I'm still much slower at climbing on the 'bent (not helped by it being a fairly hefty beast).
If you're still having control issues, I strongly recommend taking it to a park or industrial estate after-hours or something similar where you don't have to worry about traffic and putting some time into practising low-speed manoeuvres. Tight turns, weaving between obstacles, following a line or seam in the tarmac as slowly as you can without wobbling. The same while riding one-handed. Stopping sharply at a given spot, then setting off again quickly. That sort of thing. You only get to use these skills once or twice per ride when you're in traffic, so a couple of hours concentrating on them specifically can really make a massive difference.
I got hip pain for a while in my left leg only. I'm not entirely sure what caused it - it could have been an injury unrelated to the bike that just got better with time - but I suspect it was related to keeping that foot clipped in while stretching to keep the bike balanced with the other, or straining while pushing away with an over-extended leg (I always start with my left foot, because my right knee is dodgy). I've since shortened the boom and given up on remaining in the reclined position while stopped at junctions (I'm just too short to do it reliably) - either of which may have helped. It's also likely that my left leg is slightly shorter than my right (they've not been measured since my early teens, when the difference was 'negligible'), which might have had something to do with it.
Playing with position is a good thing. I find I ankle more on the 'bent than on an upright, which makes overextension harder to judge. Seat angle appears to be voodoo, and depending on the bike may influence leg extension to a greater or lesser extent. I also find that my position in the seat isn't consistent, varying with tiredness and the type of riding I'm doing (cruising vs climbing vs mucking about in traffic). Easing off a bit and spinning a lower gear is probably a good idea in general, at least until you're happy with the ergonomics.