I have the Purge Valve on my IO-360 and it appears to work well, but then I've operated a number of different injection systems and as long as you have your favourite hot starting procedure down pat, there is little to be concerned about. While I'm happy with the Purge Valve I have installed I'm not sure I would go to the trouble of retrofitting one, especially if you've not had any issues starting without it.
For hots starts I turn the pump on and purge the system while I assemble my harness. This probably takes a good 40 to 60 seconds, maybe? I'm not sure you need to purge for that long but its just a good way of doing something with the time while putting your seatbelts on. I then turn the pump off, close the purge valve, give the pump a 2 second burst and start with the mixture lean. Job done.
My purge line goes all the way back to the right tank with the rigid fuel line running parallel to the breather line along the side of the fuselage . I simply added another -4 bulkhead fitting to the inboard tank rib during construction. This guarantees no recirculation of the warm fuel. For controlling the Purge Valve I purchased a high quality locking push-pull control from McFarlane. The last thing you want is for that valve to move in operation.
If you want photos of the installation I have plenty, but its pretty self explanatory.
Just a side note - something I never considered during the build. If you are pulling the fuel from the left tank and your right tank is very full, then it will be even more full after purging. I now have a habit (and a decal on my fuel valve) of selecting right tank for purging so I can't overfill that tank. It's not a big issue, but there were a couple of occasions where I had topped off both tanks a bit too high and then flew a couple of legs where I used the purge valve. When I got back to base the right tank cap was weeping and when I investigated further (by removing the fuel cap) a few tablespoons of fuel disappeared back over the top of the wing. Lesson learned... twice. I'm a slow learner.