I have used the RAPAS for my AP1100 and now AP1600 pretty much since the RAPAS was offered to help setup in the field. The only thing I do is setup using the RAPAS and verify accuracy with a drift alignment. I could get some unguided images with my C14 f7 STL6303E setup periodically up to 5 mins on my AP1100 non encoder version using this method. The RAPAS has been one of those must have tools if your setting up out in the field each night.
I currently setup and breakdown my AP1600, AGO 12.5", STXL6303E at my RV park using my RAPAS with excellent results. I recommend to check the alignment of the RAPA when you first get it, if you elect to buy one. I get good unguided results with this setup as well up to 5 mins, maybe I could get more but I just autoguide for anything over 5 mins.
I did buy a Polemaster to test it out to see if it was more accurate but its still in the box because the AP900 adaptor doesn't seem to work for an AP1600. So right now the RAPAS is still King for my needs. One more quick observation is to make sure you look in the RAPAS centering you eye, otherwise I have noticed you can be off a little for adjustments.
Anyone know offhand if the front cap on the AP1600 is larger than the AP1100? My AP1100 is in WI and my AP1600 is with me in TX. I'd still like to do a compare of the two, maybe I will try setting the Polemaster using a dovetail mounting.