@taralp I know this is an old post but I was looking at redoing my site and URL structure myself.

My concern was losing rankings with drastic changes also. But I ran the site through a SEO tool and it looks like since this post that not only did you not HURT your rankings, the rankings skyrocketed since then,

If you are still around, may I ask were there any other changes to the site around that same time? How long did it take to make the change?

For others that may be reading this. Does Google still take URL structure changes so kindly? Will a simple redirect plugin for WordPress do the trick if I make category and url changes myself?

I want to remove "category" from the slug also and I want to merge and delete some categories and add others.

Thanks!