Hi, I devise two ways in which joining could be made:

1) As a user interface feature. I mean, no changes would be done on the wave files. In this case, joining would serve mainly to move several clips as a whole. Perhaps a "group" funtion for clips could do the same, being more transparent with the actual organization of audio?

2) As a way to create a new wave file. In this case, joining is quite equivalent to bouncing except that a) all the clips to be joined have to be in a track b) the new audio file/clip replaces the existing clips.

In both cases, the previous organization of clips dissapear, which may not be desirable (you may want to do a different processing afterwards...).
From a different POV, if you're sure enough about you're doing, you may prefer the work space to be cleaned immediately. Thus, having the option of joining (& creating the wavefile) could be useful. From the coding side, it's little additional complication, I think:
joining=export+delete+import
bouncing=export+import

A-B SWITCH
When comparing different live takes of the same passage (or different processing of the same wave), it is handy to have a button to immediately switch from one track to another when playback. This could work as follows.
Consider a new button next to the three existing ones (snap etc), wich reads 'A-B', see enclosed example artwork. When pressed, it changes to 'on', and only one of the tracks marked as 'solo' will be heard.
Which one of them? it's selected by pressing a number in the keyboard. <1> for the first solo encountered track, <2> for the second one, and so on. Up to 9 tracks could be marked as 'solo' to switch between them that way. If more than 9 are marked 'solo', the remaining after the ninth would be ignored. Default for playback after pushing the A-B button is 1.
In the most typical use, only <1> and <2> will be used, but it's good to have some 'headroom'.
An alternate approach would be that when the A-B button is on, the playback rotates among all solo-ed curves pressing a key, which could be <1> or whatever.

BOUNCE TO EMPTY TRACK
This is handy when you have splitted and processed, and splitted again... a wave, perhaps in one or more tracks, and you want to have the result in a single clip (wave), in order to delete all the previous mess and carry on working. In fact, this can be done now by using the export function, and then importing the result to an empty track. But would be more comfortable to have it at hand, and with the new clip automatically in position.
It would work in much the same way as the present export: only solo-ed track(s) would be bounced, and the resulting wave would be placed as a clip, with a suitable name, in the first empty track, or if there is none, in a newly created one.

ZERO FINDING
I think every editor I'm aware of has this feature (sometimes called 'auto zero'). Even the modest mhwaveedit has it. Basically, it finds the nearest zero in the waveform, so that you can split the wave at this point without introducing a click in the sound. In a stereo wave, a common zero in both channels is to be found, which probably requires to admit some level of error/tolerance.
In Traverso, there could be a couple of commands, <0L> and <0R>, which would place the workcursor (or the playhead for that matter) at the nearest zero to the left/right of the mouse position, in the wave the mouse hovers on.
An alternate, perhaps better, approach could be that the original position is taken from the workcursor itself, not from the mouse.

SPLIT AT WORKCURSOR
Is a complement of the previous one. A function, say <XW>, that would split the wave pointed by the mouse at the workcursor position (not at the mouse position).