Actually, there are several people on CN using very high quality mounts equipped with AEs. It just turns out that all of them are 10 Micron mounts rather than APs.
And, at least one of them, would insist on two points specific to AP’s implementation of the Renishaws . . .
1/ The installation of AE’s is such a precise affair that an “add-on” kit for them, such as AP’s can just never be satisfactory!
2/ The way the AEs are “cobbled onto” the AP mounts results in their not being true absolute encoders at all. Meaning, the AP mounts can still become “lost in space” even when encoder-equipped.
Remember, I am playing devil’s advocate here. In his defense, I know of not one soul who has retrofitted an AP 1100 or AP1600 with the encoder DIY kit.
It is repeated over and over that the real advantage to AEs is to remote operators. Getting a mount “lost” can be a real nuisance to them and having a mount that can’t get “lost” is a real plus. But, that big advantage is totally lost with APs because, well, even with encoders, they can STILL get lost.
The other advantage to the encoders is that tracking is so precise that unguided imaging becomes more readily achievable. Now, it is pointed out that with additional software, the AP mounts can do unguided imaging. And they can do this WITH or WITHOUT encoders! That said, all the unguided images being shown are from encoder-equipped 10 Micron owners. Or, so it seems.
Spending $8,500US for the encoders on an AP mount is a very hard sell. The goal in doing so has to be more than a flatter guiding graph.
What I post here is the situation as I understand it. If you are seriously considering the AE kit from AP, you really need to have a talk with them about just what it is you expect the encoders to accomplish. Just trying to flatten the guiding graph is pretty pointless. The mounts are already more than capable of faultless imaging while being guided.