I think it's a personal choice to be honest with you, u can't go wrong either way.

Some learn better by by the lvl'n process getting one skill at a time, some however can learn just fine with all those skills laid out in front of them, either way if your willing to learn then it doesn't matter if u skip or lvl traditionally.

Judging by your post u seem willing to learn so if I were u I'd buy the boost potion because either way you seem like a person who's willing to take the time to learn, plus the dps que times u complained about have got u to the point were u strated a thread about it so I'd do it.

I bought one for my alt, but I already knew how to play the job I boosted, but if think about it anytime we get a new job it's like thier boosted cause we get all those skills at once and learn em.