That's my thought exactly. If it's already got a great Jump, get the most you can for the other skills.
But the only way to get Tumble higher using Skill Focus is to max out the skill, e.g.:
Tumble 5 ranks +3 Skill Focus, Move Silently 0 ranks, Jump 0 ranks.
Otherwise, can could get the same Tumble modifier with Acrobatic by just shifting 1 more point in Tumble and end up with an extra +1 in Jump.
e.g.
Tumble 3 ranks +3 Skill Focus, Move Silently 2 ranks, Jump 0 ranks
Tumble 4 ranks +2 Acrobatic, Move Silently 1 ranks, Jump 0 ranks +2 Acrobatic
Oh, and as I said earlier Open Minded offers them the same Tumble modifier as 3 skill ranks plus Acrobatic with an additional point left over:
Open Minded gives +5 SPs, for 10 in total.
Tumble 5 ranks, Move Silently 3 ranks, Jump 2 ranks (or variations thereof).
So why do you think Skill Focus is such a good deal? You didn't seem to want to max out the Tumble skill.