Tough call, really.
The Inspo is immensly popular, and has good support through SSA Montclair, probably the largest AP dealer in the US. Training is easily available from just about any agency through plenty of instructors.
The O2ptima is off to a good start, but for local support, afaik, Ventura is the closest and only dealer. Training I don't know, but Dive Rite Express has the instructors listed on their website.
Probably the biggest difference are the electronics. The Inspo has two dependnet controllers and no seperate pO2 monitor. The O2ptima's Hammerhead has a single controller and a seperate pO2 monitor that also includes depth and time display (dive timer). Personally, I like the latter layout better. The HH on that unit includes nitrox and deco software at no extra charge as well as HUD that either gives warnings or actual pO2 readouts, plus has a vibrating alarm you won't miss.
Depending on the version, the Inspo has only pO2 displays and buzzers to warn you (Classic). With the Vision electronics you get a single display for both controllers that includes a dive timer, optional nitrox and optional trimix software upgrades and a HUD in lieu of the second handset. The latter also gives status for both controllers. Last but not least the Vision gives you yet another option, the TempStick scrubber monitor. All of which means it's a major improvement over the old Classic.
For electronics look at the pros and cons for each system and decide your preference.
The scrubber is hotly debated issue, the Inspo's axial can take normal (and more easily available) granular absorbant that costs quite a bit less than the O2ptima's Micropore cartridges. The advantage of the cartridge are much reduced chance of a caustic cocktail and absolute superb ease of use. Depth performance, at least from the data published, leaves some to be desired, though. The Inspo on the other hand has been CE rated (which the O2ptima has not) to 82 mins, more than twice the O2ptima's result.
Look at the number of dives and profiles you do, or plan to do, and see what suits you better.
The Dive Rite supposedly folds up into a carry on size package for travel as long as you leave the tanks at home. It allows either 4 ltr tanks or 2 ltr tanks to used. The Inspo won't travel as conveniently, but will work with its 3 ltr as well as the Evo's 2 ltr tanks.
Again, look at your diving and locations and see what suits you.
Last but not least, the Classic and O2ptima about the same price, while a decked out Vision costs about three grand more.
Ask you banker what suits you.
Personally, I would prefer either a Meg or a PRISM over those two units.
