Modding SDS Hammer Drills - What to look out for?

Hey everyone! I'm in the middle of rewiring my garage at the moment as part of my rack farm thread (linked in my sig) and have hit a bit of a problem whilst mounting a sensor light above the outer door. I've drilled into the concrete lintel above the door with a hammer drill and a standard masonry bit but can't get through the reinforced concrete of the lintel. It's the last hole that I need to drill to put the light up and is necessary for a fixing screw.

I think it's time that I invested in a good SDS drill for myself. As well as being good for this sort of job (the garage to workshop and coalshed to server room conversion is very much a WIP at the moment) it'll be good to have a better drill for working on mods with. Large holesaws are tough on a small drill and the one that I've been using for the past few years has seen better days. I plan on spending around £100-£130 on a drill and a carbide SDS bit suitable for drilling that last hole in the lintel. If I am to also use it for drilling holes in metal, wood and plastic It'll need to have an interchangeable chuck too, so it can accept standard bits. I like Bosch power tools. In fact if I'm buying it locally it will almost certainly be a Bosch because I know a couple of employees at the local hardware shop who give me a discount on tools and they stock a large range of Bosch products.

All I'm asking is what to look out for in an SDS as I've never bought one before - I did use someone elses on a job for several weeks about a year ago, so I think I know enough about them to make a decision on which one is suitable for me - but maybe you guys know more on the subject than me and can advise me on what's good and what isn't

Thanks in advance!