modified suspension
 

This is possibly a question that only a novice would ask but so be it.
What difference does it make to the handling/comfort if I change the stock fork springs and rear mono shock on my 3AJ tenere with those of technoflex/wilber (progressively wound front springs)?

changing the suspension to wp or others like öhlins will cause a significant and positive change in handling.
front fork will be more sensible but also more strong when it comes to jumps etc., rear shock will perform much better, especially when travelling with heavy luggage.
you should inform yourself about adjustment of the suspension units. many people ride with a too hard suspension set-up (obviously the didn't fully understand the meanig of 'hard-enduro').
usually the proper supension setting is described in the manual of the manufacturer.
regards
klaus