My latest observations on being a summoner after the recode:
1) The first skill I would buy on is defense. Get a little, test it
on a little mob, and if it's good try a larger mob, until you get
around the size of the stuff you fight normally, slowly raising
absorption as needed. Frandlan thinks 10 persistence is enough
for his needs, and I agree with him. And to give you higher mages
an idea, 20 absorption was not enough for me, as a 125k testing
monster who only does physical dmg was able to hit me for 50-75
per hit through my stoneskin.

2) As for summon skill, it seems a roughly even distribution is
the way to go, with assiduity possibly being higher. What I found
was higher exaction made my conc go up faster with the same
summons. So don't raise assid until you think it's enough and then
pour all the rest into exaction...raise them both slowly and test
as you go along. Something else I suspect but haven't been able
to test extensively is that mentals become relatively worse
compared to mon6 as your exaction gets very high. I think
perhaps the dmg curve for mentals rises faster w/ exaction,
but then plateaus out and lets mon6 catch up. The two data
points I have are exaction 45 (mentals kill approx. 30-40%
faster than mon6 but require constant recasting as the conc
curve goes through the roof) and 51 (their damage seems
about comparable)...plus all this was against the testing
monsters, some other mobs may be more weak to one or the
other. Mentals always tank much worse than mon6, but that's
ok since I usually end up needing to send them away after about
35 round anyway.

Anyway, I haven't given any conc numbers yet. My first go at
51 exa and 30 assid, conc was by far the limiter. 2 mon6's
would raise my conc almost 2% per round, and to kill a 125k
testing monster I'd need to send them away and regen conc
twice. 2 mentals (sent away at 30 round intervals) killed
about the same rate and took far more sp for the battle.

45 of each seemed to work much better. 2 mon6's raised
conc less than 1% per round, while mentals only lasted
slightly longer before have to sendaway (maybe 5-10 more
rounds). Mentals did do significantly more dmg relative to
mon6, and going with a combo of 1 mon6 and 1 mental
sped the battle up by 30%, for quite a bit more sp due
to recasts and major globe.

Overall, there's a bit of leeway for how much assid you
need for a given exa. Less assid means you'll be sending
away and recasting more, then you put more of a burden
on your sp regen. More conc and you can sit for longer
with the same set of summons, switching tanking as
necessary, this strategy is also a lot safer.

3) Intrinsics: You will probably want to very nearly max
out your potential. Do potential and your combat skills
before the other intrinsics (although feel free to buy
perhaps 20 renewal first since it's so cheap and doesn't
take away from any other skills) because you need to be
able to fight and trust me, you don't need to worry about
sat. Experiment a little with renewal, but don't buy too
much because IMO it's not worth the cost much past 25k
gxp per point. Capacitance I was doing fine with 0 against
the 125k mobs. So after all my other skills were set I
spent like 10k to get some, just in case, but it's pretty
clear that it won't be a big necessity for summoners,
at least the way things are now.
                                  -Sculder