It's a bit of a different style of shooting. On a Technika, you either focus on the groundglass view-camera style, and there's some delay after focusing before you close the shutter, stop down the lens, put in the filmholder, pull the darkslide, and make the exposure, or you can compose on the groundglass, load the filmholder and pull the darkslide, check focus with the rangefinder, then check framing in the viewfinder before making the exposure. It's not a single-window rangefinder-viewfinder, so you can make more dynamic portraits than you can with a view camera that doesn't have a rangefinder, but not as dynamic as you can with an SLR or TLR, where you can focus and compose right up to the instant of exposure.
You have more flexibility in terms of lenses with a Technika than with a fixed-lens camera, but for portraiture, you'll probably use mainly one lens anyway, possibly two, if you need a range for, say, tight headshots and full length group portraits. If you like the Rolleiflex, you could use a Tele-Rollei and a standard Rolleiflex and have the same flexibility with the ease of use of a TLR.
Yet another option is something like a Graflex SLR, which would give you SLR composition and focusing with a large format negative, but if you're using strobes, I don't think you can have sync and the SLR functions at the same time (in their day, the options were open flash technique or FP flashbulbs that would burn over the full length of the focal plane shutter exposure).
There is also the Gowlandflex, which is a 4x5" TLR that can be set up with interchangeable lenses. There were also 5x7" and even a half dozen 8x10" models, but most of these are 4x5". This will work with strobes. Normally they are set up with a shutterless viewing lens matched to a shuttered taking lens, and there is a cam dedicated to the focal length of the lenses that adjusts for parallax as you focus. It is possible to change lenses on these cameras, but I'm not sure it's easy to do.