Now these are incredibly sought after in the guitar community at the moment, it's not just a thing on TFB, but over the pond too, TGP is all over them, to the point that the American's are ordering from the UK suppliers and accepting the import taxes hit. Anyway, I have been in the fortunate position to own three at the same time... two variants of the 24v and the regular 9v model. Here's my thoughts:
Firstly, this is an insanely good pedal in any guise. It is different to almost any other gain pedal I've tried and has a clarity to it's tone that you don't normally get from overdrive/distortion pedals - something that is probably down to it being a pre-amp rather than a regular transistor overdrive. As a result it works great in a live mix.
The 9v version is very thick and gainy when running on a 9v input. It sounds best to me on the low gain side, which in itself gets almost as crunchy as the high gain side of the 24v! The 9v pedal high gain side (running on 9v input) is a very thick fuzz, the kind of gain tone that my Lazy J J20 amp unfortunately just doesn't work with. Other amps would probably work better with this type of tone as a caveat, plus there are internal trim pots for the gain which you could adjust down if you were only going to run it off a 9v power supply.
The 24v pedal, whether on the low or high gain settings, simply sounds better for my personal tastes. Lower gain (in relation to the 9v), more articulate & open, clearer, higher headroom. The 9v pedal vs 24v is like a totally different gain pedal. You can get a lovely crunch from it, and on high gain, a lovely clear fuzz.
The big attraction of the 9v version for many is that it can work at different input voltages which has a drastic affect on the tone. I ran the 9v pedal at 9v, 12v and 16v. Each time I increased the input voltage it sounded better to me, although due to my power supply I couldn't hit it with the full 24v...and as a result it never sounded as good as the bone-fide 24v versions, especially on the high gain side. If you have a tricked out power supply then the 9v will give you more options because the 24v version runs only on a 9v input which it then transforms to 24 volts internally.
So just looking at the 24v pedals now : 1 footswitch vs 2 footswitches? Tonally they are similar, there are slight differences but they are minimal and probably down to component tolerances. The duel footswitch adds an easy way to select between low and high gain sides so in operation it's a two channel pedal and for many that added flexibility is the killer app. To counter that advantage, on the 24v single footswitch version, the selector switch is three position (low, medium and high gain). It's gain range is a little wider than the duel, not much more, but it's nice to know it's there should I need it! The lack of a second footswitch does render it a "single channel" pedal when playing live though.
In summary, the 24v version is the one I'd pick if I was shopping again for a Broadcast (unless I had a high voltage power supply). As I am a set and forget kind of player who's happier with less switches, my pick is the 24v single footswitch iteration, but you can't go wrong with any version really. ***Postscript***
As a postscript to the review, based on a few questions that I've received, I will add that the Hudson Broadcast is not a highly compressed, soft or smooth overdrive so I can see why some will not like it. It’s very clear, very immediate and raw sounding, it’s a gain pedal without a safety net or anything to hide behind! Mind you, it’s this rawness that I like, it's different to the majority of overdrives out there and it works great with my warmly voiced tweed deluxe style amp.