To answer your initial question, I have a co-worker who has been running the 88g version of the fluval disposable cartridge CO2 setups at home and he loves it. You do have to manually turn it on and off daily, but for what it is and how small it is, it's pretty nice if you understand the long term cost of the canisters.
I think for a small 5G tank, the one you have would be perfect for an environment with less space that you wanted to run CO2 in
As far as long term, I know I already mentioned it when I picked up the Chi, but I've been running an Aquatek paintball regulator. It's ready to connect to the tank out of the box and was about 95 shipped. Plugs right in to my timer, uses no tank adapters and it includes a bubble counter/check valve. Admittedly not the raddest looking bubble counter, but it's there and it does its thing. I just picked up a second one to run on my 35 gal planted tank at home and ordered the accessories from one of our vendors since they have the diffusers and drop checkers and tubing etc pretty cheap.
Total spent about $155 for a complete setup with regulator, bubble counter, drop checker, tubing, diffuser and paintball tank (including $20 for the tank, filled at the paintball store in the heath mall)
Good luck with the setup. Stoked to see both of them flooded