A nice little thing to add to the renderer options would be a little button bringing up an advanced options window where you are offered sittings like:

• changing the fade time of the persitent view (fade by seconds or by frames so it won't keep fading as you pause) Uses: Monitoring particle travel, creating other optical effects.
• changing the blob radius: Uses: Just optical effects.
• changing the heat display range (for example everything below 1000K is displayed as blue (like 0K in standard heat view) and everything above 1200K as pink (like 9999k)) Used: Observation of a specific temperature range for example heating devices in lasers where you can now analyze the heat transfer to the photons in detail.
• create custom views and assigning them to hotkeys (heat gradiend and alternative velocity displays are not used as often as others) Uses: Depending on what types of saves you usually create you can create your own view that displays the properties you are interested in best (see note above).
• modify existing views with the option to reset them to default Uses: You don't like the long fade time of the persitent view? Change it to 13 frames for example.
• etc.

I just wanted to give examples of some options and I bet you can think of many more.

I don't know whether this is hard to implement but at least it won't increase the size of the save file since the view isn't saved.