150 psi induction pump. You'll probably only get a true 120ish max psi out of that, plus they don't last as ling as the higher psi pumps. I know as I had two machines with those pumps. Plus you'd get a better/quicker clean with a higher psi. Something around 200 - 250 psi is enough.
Since you have that extra power in extraction, you can opt for bigger jets on your wand, making even quicker cleaning.
The suction on the turbo is fantastic. It beat another top end porty, when independently tested using lab equipment in the suction department. It'll beat the express hands down on long hose runs, so I presume (I'm not an expert like john) it'll also beat it in short 25 feet hose runs. Can only make sense.
Like John said, price makes a difference. Also depends how used and abused the turbo is since its second hand. Make sure you have a good look at the machine inside and out before parting with cash. Also have a go at it, look out for any leaks.
Having said that, its an easy machine to work on if you need to change parts in the future.
Does the Airflex not come with any hose or wand?