I'm not sure about running the old Vue 2016 and the latest subscription Vue side-by-side. It's a key un-answered question, that will be holding back many old users from even trying the trial for the subscription version. The FAQ has no answer.

The basic questions to ask yourself, assuming you're on Windows, are:

Q. Do I rely on many key Python 2 scripts in Vue? 

A: If yes, then stick with Subscription R4 and Python 2 (but you will loose .TER import). However, note there is "no Python scripting" for the new Creator subscription edition.

Q: Am I a movie studio guy who exports all the time to other software and renderers? 

A: Then get the latest Subscription R6.

Q: Do I know and use Substance / displacement a lot in Vue? 

A: If yes, then get the latest Subscription R6.

Q: Am I a big cloud-builder and fiddler, and also happy to wait ages for a render with a big fancy cloud-scape? 

A: If yes, you want the subscription Vue. If you just slap some clouds photo-stock onto the render in Photoshop and hit the blend-modes and the Soft Eraser, then no.

++

Ok, that said, here is my skim of the changelogs:-

February 2021 (subscription R6, current)

* Better compatibility with Cinema 4D, Maya, Lightwave, Arnold, Redshift and V-Ray, V-Ray Next renderers.

* Various improved export options.

* Export to USD and its variants, with Ominiverse profile.

* "The PathTracer now supports NPR" (sketchy rendering, lineart etc).

* SVG support for splines import.

* "Many content browsers now support multi-selection to load objects, plants, rocks, metaclouds, cloud layers".

* "Fixed DEM import dialog" (again).

August 2020 (R6 hotfix)

* "Massively reduced the memory usage during render, for EcoSystems using SolidGrowth species".

* Various Mac fixes.

June 2020 (subscription R5)

* "Displacement has been improved dramatically and offers three new subdivision strategies".

* "Avoid losing displacement whenever one adds a material layer".

* Better support for Substance materials.

* "Improved mesh smoothing algorithm performance (up to 4x faster), which also benefits to displacement mapping".

* "Optimized displacement mapping preparation when there is no subdivision (4.5 x faster)".

* Integrated de-noisers.

* "Path Tracer now supports semi-transparent and semi-reflective materials".

* "Further optimized rendering of billboards with the Path Tracer (patched for full CPU implementation)"

* "EcoSystems can now be hidden - set displayed instances to 0 in the VUE options (can be helpful in large scenes)".

* Reworked godray atmosphere scenes.

* "Terragen terrain file support is back".

* "Allow loading non-geo-located pictures as heightmap-based terrains".

* "Import real-world terrain texture data from two remote imagery servers: aerial data" (very low def outside the USA).

* Much wider support for various .TIF and .TIFF formats.

* Allow sharing the same PlantCatalog folder for both VUE and PlantFactory.

* Improved Python documentation.

* "Removed Python 2.7 ... in favor of Python 3.8" (presumably many old Python 2 scripts now no longer work from this version onward, then).

December 2019 (R4)

* "Automatically retrieve real world terrain data as heightmap or procedural terrains", into Vue.

* Importing a DEM file now offers the choice between creating a Procedural Terrain or a Heightfield.

* Cloud morphing introduced.

* Allow drag & drop from Atmosphere browser, and to the Vue scene from Windows.

* Reworked and optimized FBX import.

* Fixed transparency handing with MakeHuman figure imports.

* Supports latest MacOS at that time (Catalina).

August/September 2019 (R3 and 3.1)

* "Dropped support for the Terragen (*.TER) heightmap format" (was re-introduced in R5).

* Fixed broken Python function AddTerrainFromMap.

* "IceRings and Rainbow effects work in photometric mode".

* "Improved quality of OpenGL preview of atmosphere".

* "Created a button to hide downloadable content".

April 2019 (R2)

* "SkinVue fixed and added to VUE". (Important for Poser scene imports with prominent figures).

* EcoPainter now also has the ability to load native objects.

* Added the ability to copy/paste images in the material and function editors (from the popup menu).

* Fixed DEM import dialog.

February 2019 (1.0 06378)

* Fixed integrations with C4D, Lightwave, Maya etc.

* General post-release bugfixes.

December 2018 (Subscription 1.0)

* Standard metalness/roughness PBR and Substance support

* New way of making clouds (turn any 3D mesh into a volumetric cloud).

* UI redesign.

It appears no-one has tinkered with or removed the long-standing Poser scene import support.

No mention of big render-speed boosts, in any changelog.

Full technical notes are at: https://info.e-onsoftware.com/release-notes

---

Learn the Secrets of Poser 11 and Line-art Filters.