One thing to keep in mind...
While you may be running the 1.0 housing with the gate shut, and making happy boost/power/response, the 1.15 housing would make more power, around the same boost and very similar "response", as long as response means engine power, and not boost needle movement. This is because it "handles" the exhaust side so much better (efficiently). And unless you've got it wired shut/welded, it's hard to say for sure the gate isn't opening on you. In my experience anyway.
On the dyno my truck made more power at all points from 1000 to 3600rpm with the 1.15 housing on the 38R as a single. There was not one spot where the 1.0 housing touched the 1.15 on power or torque.
Just throwing that out there.
At lower altitude, that might be so. Heck, with stock injectors, there's no need for a wastegate on the 38R in either the 1.0 or the 1.15 configuration. Also, I have ridden in Jacob's truck back before he made a few changes to his truck, and I've heard the 38R surge under his hood. Mine doesn't surge, but I know better than to say that these turbos are surge free. The 1.15 housing does help with surge issues. So that can be another advantage of running it over the 1.0 housing. So yeah, I can see where you are coming from Charles. The best combo can be found with a little trial and error, and a dyno or drag strip is definitely handy when trying to dial in your combo.
I can only speak from what I see, but up here in Colorado, turbo lag is a huge problem. Even stock turbos are laggy turds, and that lag creates big problems for daily drivability. It's much more difficult to squeeze out power below 2000 RPM's (and especially below 1500 RPM's) at high altitude than it is at sea level. I think that's where having the 38R running a 1.15 housing on a stock injectored truck might have some issues. But that's my opinion. Maybe one day we can find out for sure. Would be fun to have a .84 housing laying around too, just to do a 3 way comparison.
Oh and don't worry Charles, there's no way my wastegate opens up.