I can't tell anyone else what to do, just say what my experience is.
Been using Leicas for about 40 yrs. In the same time frame though, I've always also owned an SLR, and glad of it. It's always been true that rangefinders have their weaknesses (as do SLRs) and that hasn't changed with digital. If you're like me and like to take a wide range of subjects, then having both systems is a big convenience.
I've got a Visoflex. I've used it for macrophotography, and telephotography (have a 400mm Telyt, great lens). It's doable, but IMO an SLR gets me a lot more keepers.
I know all the techniques for pre-focusing, hyperfocaling, and using short focal lengths for greater DOF, but when it comes to capturing erratically-moving subjects like kids and pets with a portait-length lens at wide apertures (for action-stopping shutter speeds, and subject isolation) a modern multi-sensor predictive-AF SLR gets me a ton more keepers than the Leica despite all my years of practice at it.
Yes a D700 (or in my case a 5D) and a fast zoom is significantly larger than a Leica with a small prime. But subjects know a camera regardless of it's size, so if a DSLR makes anyone uncomfortable, it's likely because the photographer himself is telegraphing his own discomfort. Just check out the # of very successful photographers who make gorgeous people-photographs with huge DSLR's. I use a Leica as my travel camera because when I get on a bus or metro or sit down at a cafe I can put the Leica in my coat pocket or a little bag that rides close to my body, so I can enjoy the non-photographic moments of my trip more than if I had a large, bulky camera/camera bag to deal with. But there is a trade-off. I can't even begin to account for the number of great shots I've missed switching lenses, which I would have gotten if I'd merely been able to twist a zoom ring.
Lastly, there's the issue of service. Here in the USA I've never had Leica service that didn't take at least a month, and sometimes longer. When I was shooting film, a second body wasn't that major an outlay. A second M9 is well beyond what I can bring myself to spend. OTOH, my 5D recently needed service and it was back to me from Canon in a week. Plus, I had my 20D to use in the meantime. A backup DSLR is a few hundred $, not several thousand.
In the end, much as I enjoy the Leica and always have, if finances forced me to settle on one system alone, it would have to be a DSLR.