By "Pro-Line," I wonder if you are referring to the 1000ml bottles or the 5L silicone-free products with the black labels? I know Detailer's Paradise carries the 1000ml bottles but I'm not sure about the silicone-free 5L jugs. If you contact Open Road, I'm sure they would tell you what they can get, here is the email listed on their site: sales@openroadmotoring.com.
BTW, the MP in the 1-liter (round) cans is the "Pro version". It's a little different from the (pink) MP in the smaller rectangular cans. Slightly more abrasive ( a subtle but good difference, IMO) and with less wax. I'm happy with the Ultra, PP, Pro MP, and WPS...gee that sounds silly who *wouldn't* be happy with four different grades of user-friendly polish!?!
I haven't opened my round 1-liter can of PP yet, so I dunno if it's different from the stuff in the smaller, rectangular can...if you care, you might check with Mike at 1Z.
Sorry I didn't get back on this sooner, I figured somebody from1Z would respond ( seemed to get better/quicker responses before they changed this feature here at Autopia). I got mine from:
The WPS should work fine after PP if you want to skip the MP. I'd probably just do a quick pass with the (pro) MP anyhow though but that's just me. You can go straight from Pro MP to your LSP.
The only differences in use are that the Pro MP seems to be a little more like a "regular polish" than the Consumer MP, which is almost like a cleaner wax. So the Pro MP won't stay wet quite as long when you're working it since it has less wax/etc. in it. But it's not a huge difference that you need to compensate for. Pretty foolproof stuff, by hand/DA/rotary.
FWIW, the WPS *is* about as foolproof as products like this get.