I haven't seen the magazine, but if you are selling advertising space, then I'd agree - it is a case of something for nothing. Unless you're producing the magazine "out of pocket", you're not on a level playing field with the folks that are supplying the content. I'd argue, if you are selling ad space, then you should be paying for content. Otherwise, you're taking income from the people you rely on to be able to produce something advertisers want to spend their money on.
I also get the fact that a lot aspiring photographers want/like to see their work in-print, and there will always be some willing to take "exposure" over cash. I guess in the end, Jack is right - individuals can decide for themselves what's fair trade for their work.
Brilliant images - especially the one of the lemon under the boat. Very nice. IMHO, the collection seems balanced with typically (and very good) classic views as well as interesting non-classic images! Great work!
In addition to the comments already, it appears as though the DPV and some other piece of gear directly behind (above) it look parked on the coral. As a marine biologist, and u/w photographer (of sorts), I understand what takes place to carry out such work. However, I think this image would have been best left in the confines of a harddrive.
I regularly dive and shoot with a DSLR in doubles with an isolation manifold, but the only "sidemount" experience I have is carrying stage bottles (AL 80's) and deco bottles (AL 40's).
I think Timmoranuk explained things very well, although I have a minor comment on #5. If you have an actual manifold failure, and have to close a post and the isolator, you only have the gas remaining in the tank you're still breathing from - the point is a bit moot, because a failure of that magnitude would signal the end of the dive anyway.
One of the immediate benefits to having your redundancy built into the rig on your back, is that it is largely out of the way of you shooting. No bottles up-front means lots of space for the camera and you to work. I'm not sure what the sidemount folks would say, but even a deco or stage bottle upfront can be a little in the way at times. I've gotten used to it, but its something to consider.
Also, I rarely find the weight of a set of doubles to be an issue - in fact, I now prefer it to single tank diving if for no other reason than 12 lbs on the belt is a lot more comfortable than 26! In FW with steel doubles - assuming you are in a drysuit and wearing a wing/BC, you'd likely not need much weight on the belt at all.
The other option is to wear a pony bottle. Someof the solo divers out this way tend to use them, usually an AL 30 (sometimes a 19) and only use it to get themselves to the surface if something goes wrong with the primary gas supply. As you probably know, the trick to making that work is to know your SAC rate and then calculate from what max depth you could make a safe, controlled ascent - including a safety stop, then never go below that depth.
As for being able to reach the valves, that just takes practice. Anytime I'm sitting around, I alternate having my arms folded behind my head like I'm reaching for a valve in order to keep stretching the appropriate muscles. Apparently, reaching back for the top-side of the head rest in your car/truck is also a good way to develope the needed flexibility (best done only at stop lights... that are red).
I'll wrap up by saying I really enjoy the peace of mind I have while diving backmounted doubles, but they do incurr some responsibility on the part of the diver in order to get the most out of them, and like Timmoranuk, I can only handle one system too - especially while trying to shoot!
Hopefully, the folks with real sidemount experience can/will add to this for a more balanced perspective!
Hope this helps, and good luck with whatever you decide.