Here is the link to the photo http://www.faucetdirect.com/index.cfm?page=product:mediaGallery&uniqueId=2004458&filename=5543image1337100349.jpg

I can't say if Hansgrohe handshowers are the "best" because I have not tried that many, but we have been very happy with the last two and are installing a third. The Raindance bar has a channel down the middle. There is an "arm" that arcs out to hold the handshower and the arm travels up and down the channel. There is a hinge in the arm that lets it be turned left or right. The handshower rests in what looks like a ball socket at the end of the arm that lets it be tilted forward or backward. It is hard to describe. You should go look at one in a showroom. Hansgrohe makes several wall bars, but the Raindance Unica has the widest range of pivot adjustments.

I used Hansgrohe in the Retroaktiv line (Tango, I think) with Moen Kingsley lav faucets and towel bars. I am happy with the bar and hand-held shower, and stylistically they complement the Kingsley line well. I don't know if you have already put in your shower valve, but I really like the way the Hansgrohe's Thermostatic one works. There are other threads about it. It is not cheapest, but a good value for the quality. Grohe is perhaps even better but also significantly more expensive. If you already have the valve, it won't make any difference.

It is possible for you to do a retrofit, but the ease of it might depend on a properly configured slide bracket being available. Obviously the bracket would have to be sized to fit the vertical tube. If the bracket is a 2-piece "clamp-on" type of thing, then that's easy. If it's not and you'd have to unthread the shower head off the vertical to install the slider over the vertical tube, then reassemble. That might make it difficult. Another consideration would be if there is enough clearance between the vertical tube and the shower wall for the sliding bracket to fit and be functional. So, no promises. Another option that will definitely work would be to abandon the idea of the infinitely adjustable slide and to just buy another fixed wall mount bracket to hang the handheld from. You could have one bracket mounted low and the other higher. Two locations. Less flexibility, but much easier. The bracket part number appears to be 96532xx0, with the "xx" being the finish. Chrome is usually "00", brushed nickel "82". So your number should be 96532820. The brackets in chrome are usually $15-$30, nickel could be that or doubled. Hansgrohe tidbits can be difficult to source, especially if the price has been lowered due to it being discontinued. You can look beyond your specific product model though, as another type of hansgrohe bracket might hold your handheld head just fine.