That's where my optimism limiters were triggered: sending something in the general direction of earth is all nice and well, but receiving that signal, sent from the confines of a "DVD sized" emitter, against the backdrop of a nearby star? They should try to find a way to harness optimism for propulsion...
Radio encoding has come a long way since then. In particular ft8/js8call uses an encoding that can communicate at over 20 db below the noise floor, allowing communications across the earth with a few watts which involves many 1000s of miles of atmosphere, bouncing (poorly) off the upper atmosphere and the ground many times.
If we launched one an hour at 5% of C (better than today, but much worse than the goals of the project) they would only have to communicate across hops of 3 light minutes, er about half that since 5% of C is the final velocity not the average. Considering voyagers success at 21 light hours and the improvements in encoding that sounds quite feasible.
But also, interstellar vacuum is very, very empty. Encountering a speck of dust even in that distance with that size of a probe is a pretty negligible risk if I recall correctly.
A paper produced looking at the feasibility of such a system https://arxiv.org/pdf/1604.01356.pdf says
>A critical issue will be the stability of the sail. There are a number of perturbative effects. These include laser instabilities and laser mode issues, differential forces on the sail and mechanical modes in the sail, heating of the sail and laser pointing instability. >This is a complex sets of issues that requires a significant amount of research and development. This will not be trivial.
I believe these issues are show stopping rather than "not trivial" You can never fabricate a probe of small enough mass which has enough area for laser propulsion to work effectively whilst not tearing itself to pieces or overheating (at least not to anywhere near relativistic speeds).