At one time flat stitches (composites, panoramas whatever) could only be done well with shifting lenses. But with software these days, rotating your camera around the nodal point with a calibrated spherical head can produce results indistinguishable from those made with a flat stitch. With focus stacking software you can increase depth of field. With CS6 you can simulate miniaturization effects from aggressive tilt adjustments.
There is no feature of a tilt shift lens that cannot be replicated with current high quality bodies, lenses, software, and tripod heads. If you want a TS lens as a way to inspire creativity, go for it. If you think you will create more perfectly sharp images with less fuss, think again.