UPDATE
OK so the functionality for “permanent” controller assignment of insert slots seems to exist. We can edit the XML file in a text editor directly to get around the currently limited menu options in my previous image.
In the attached image, the settings for Pad 1-2 (which have plugins inserted) were duplicated for Pad 3-8. This allows permanent bypass toggle of inserts 1-8 for currently selected track in the mixer, even if plugin is changed in that slot.
So the functionality seems to be there; we just need the Value/Action menu options for insert slots (like we have with sends already).
For reference, text of this XML file follows:
<?xml version="1.0" encoding="UTF-8"?>
<remotedescription version="1.1">
<ctrltable name="Standard MIDI">
<ctrl><name>pad grn 1</name><stat>144</stat><chan>0</chan><addr>16</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad grn 2</name><stat>144</stat><chan>0</chan><addr>17</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad grn 3</name><stat>144</stat><chan>0</chan><addr>18</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad grn 4</name><stat>144</stat><chan>0</chan><addr>19</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad grn 5</name><stat>144</stat><chan>0</chan><addr>20</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad grn 6</name><stat>144</stat><chan>0</chan><addr>21</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad grn 7</name><stat>144</stat><chan>0</chan><addr>22</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad grn 8</name><stat>144</stat><chan>0</chan><addr>23</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>fader grn 1</name><stat>176</stat><chan>0</chan><addr>48</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>fader grn 2</name><stat>176</stat><chan>0</chan><addr>49</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>fader grn 3</name><stat>176</stat><chan>0</chan><addr>50</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>fader grn 4</name><stat>176</stat><chan>0</chan><addr>51</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 1</name><stat>144</stat><chan>0</chan><addr>36</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 2</name><stat>144</stat><chan>0</chan><addr>37</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 3</name><stat>144</stat><chan>0</chan><addr>38</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 4</name><stat>144</stat><chan>0</chan><addr>39</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 5</name><stat>144</stat><chan>0</chan><addr>32</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 6</name><stat>144</stat><chan>0</chan><addr>33</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 7</name><stat>144</stat><chan>0</chan><addr>34</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>pad red 8</name><stat>144</stat><chan>0</chan><addr>35</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>fader red 1</name><stat>176</stat><chan>0</chan><addr>64</addr><max>127</max><flags>1</flags></ctrl>
<ctrl><name>fader red 2</name><stat>176</stat><chan>0</chan><addr>64</addr><max>127</max><flags>1</flags></ctrl>
</ctrltable>
<bank name="VST 1-16">
<entry ctrl="pad grn 1">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot1:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="pad grn 2">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot2:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="pad grn 3">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot3:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="pad grn 4">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot4:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="pad grn 5">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot5:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="pad grn 6">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot6:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="pad grn 7">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot7:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="pad grn 8">
<value><device>VST Mixer</device><chan>-2</chan><name>inserts/slot8:bypass</name><flags>256</flags></value>
</entry>
<entry ctrl="fader grn 1">
<value><device>VST Mixer</device><chan>-2</chan><name>panner:panX</name><flags>0</flags></value>
</entry>
<entry ctrl="fader grn 2">
<value><device>VST Mixer</device><chan>-2</chan><name>panner:panX2</name><flags>0</flags></value>
</entry>
<entry ctrl="pad red 1">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot1:on</name><flags>256</flags></value>
</entry>
<entry ctrl="pad red 2">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot2:on</name><flags>256</flags></value>
</entry>
<entry ctrl="pad red 3">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot3:on</name><flags>256</flags></value>
</entry>
<entry ctrl="pad red 4">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot4:on</name><flags>256</flags></value>
</entry>
<entry ctrl="pad red 5">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot5:on</name><flags>256</flags></value>
</entry>
<entry ctrl="pad red 6">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot6:on</name><flags>256</flags></value>
</entry>
<entry ctrl="pad red 7">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot7:on</name><flags>256</flags></value>
</entry>
<entry ctrl="pad red 8">
<value><device>VST Mixer</device><chan>-2</chan><name>sends/slot8:on</name><flags>256</flags></value>
</entry>
</bank>
<bank name="VST 17-32">
</bank>
<bank name="VST 33-48">
</bank>
<bank name="VST 49-64">
</bank>
</remotedescription>