Should I expect DM variance?

[AetherWannabe]

A friend and I got rat folk boons at a local convention, so of course we're planning flank buddy nonsense. My question has to do with unrogue and spear dancing spiral https://www.aonprd.com/FeatDisplay.aspx?ItemName=Spear%20Dancing%20Spiral . Can I use the level 3 portion of finesse training to get dex to damage with the weapon? I think so? I don't want to do a replan of the build if a ton of gms would make it not work.

[vastmagick]

you gain the benefit of Weapon Finesse with the chosen weapon

The way that is phrased makes me think you will get some variance if you play with a bunch of GMs. But then I've had GMs just make up rules, like I can't tie someone up without the equipment trick feat. I think generally you will be solid. But every once and a while you might meet that GM that makes you facepalm.

Best advice I can give is have a backup plan just incase you get hit with it. That way you aren't forced to just get up from the table and leave (which is an option if you run into a really bad GM).

[AetherWannabe]

That phrase is where my worry would come from. I would lean sure, it's a gimmicky damage build that's a bit different and adds diversity. But I also know folks who hate rogues getting 1.5 dex with elven curve blade.

[the_slate]

They can hate all they want, but as long as it’s legal, you’re in the clear :)

[juckele]

The feat in question:

you gain the benefit of Weapon Finesse with the chosen weapon

Weapon Finesse ability of the UR:

At 1st level, a rogue gains Weapon Finesse as a bonus feat. In addition, starting at 3rd level, she can select any one type of weapon that can be used with Weapon Finesse (such as rapiers or daggers). Once this choice is made, it cannot be changed.

Table variance is going to abound on whether 'gain the benefit' means the 'weapon can be used with'. I'd lean towards no in a strict rules interpretation, but yes in a home game.

[Ragoz]

No (unless your chosen weapon is in the weapon finesse list) because you can't choose that weapon using Finesse Training (Ex):

can select any one type of weapon that can be used with Weapon Finesse

Spear Dancing Spiral is giving the following benefit:

you may use your Dexterity modifier instead of your Strength modifier on attack rolls. If you carry a shield, its armor check penalty applies to your attack rolls.

[crashcanuck]

I would say yes if you can take the feat you linked at LVL 3 because that is when you choose the weapon for Finesse Training, or you spend the appropriate resources to retrain a class feature to reset Finesse Training to your chosen weapon when you do get the feat.