Ah, Marty beat me to it!
I've never seen them come up behind a pad like that, but that doesn't mean it's wrong. Others will weigh in. I can tell you that based on how I've modified my system, and how others here have, you definitely would not want them to come up through the pad. I know that modifications, additions, repairs can sometimes mean digging up pipe below the surface. Which might also be the reason you want them in front?
I can also tell you, from my own experience, that if you want your wall to look neat and tidy, you're going to have to stand there while it's done and direct the installer. (Which will make him insane, but too bad.) You might luck out and get one with the level of OCD you and I would want, but we are exceptions, and they'll as often as not put stuff where it's easiest for them. Or get them close to neat, but not neat enough for people like us. No pictures of mine for you, I didn't watch him the whole time, so mine looks like crud.
The reality is, no setup will ultimately look "neat and tidy." It's a collection of ugly machines and ugly pipes and ugly wires. No positioning is going to change that fact. The only way to appease your aesthetics about neat? Put it together with servicing in mind, then hide the whole mess somehow.
Oh, one other thing... I have an EasyTouch, an SWG transformer and a breaker box strapped to my wall, with flex conduit running between all. If you're planning on having any or all of those, Pentair (if you're sticking with that brand) sells a controller that has all three of those things in one box. That's what I'd do differently next time...