You're asking the same questions that I asked, back when i was trying to make a planner, and i still don't have answers but Seki's above looks like some gold.
So if you're taking dev requests...i have a few, based on some features i was working on:
1) I want a planner that will allow me to plan a build, and save that build plan, with a name. Then i plan a new build and save that one too. So more of a planner database, with numerous builds saved. Then when i start a new build, i can use a drop-down to choose an existing build as a template, which pre-populates all fields in my new build record. I then change it, name it, and save it as yet another build record. It has a field called "Name" which is unique, and a field called "Reference Build" or something like that, which is the build i used to start this build, or "new" by default.
2) I want the above planner to allow me to track the actual characters i register in-game, not just builds. So i start a new character record, use a drop-down to choose a build from the list (above feature), and pre-populate all fields. Then change it to match the alt i have in-game, and add the Char ID (from the game), and track tons of stuff related to him. (So it's a small database, not just a dynamic tool). Character records should also include Season number.
3) The ability to choose a weapon is excellent! I would want a planner to start with my weapon choice. That decision should drive a Sight range value which imo should be clear in the planner so you know if the build has enough, ie the Sight value turns green if it exceeds your gun range, red if it falls short, or blue it it's a match.
4) Devs like you are awesome. Thanks! But ppl come and go and old planners don't get updated because, well life happens. So i want a planner that allows me, the user, to make perk/trait changes. If the user can edit the perks and traits (and likely more), then we're not so dependent on you to keep updating the planner.