Just my 2 cents: lipos are the rave right now because they're "new" so to speak with the boating world. Wait until the Li-ion catch up like A123s and then everybody will be going crazy over those (probably another year-maybe shorter if Wazool likes them). Then everyone that dumped 1K into the lipos will be wishing otherwise.
Now my 3 cents: the rules have adjusted to make room for lipos this year at the cost of pushing NiMh out the door. Usually, the new kid on the block (lipos) has to bend for the ones that have been on the block. I know I'm looking at this in a different perspective, but the course length will be extended to push out NiMh, or you'll have to put so many cells, you'll look like a battleship sitting in the water.
I'm done with that.........I haven't done a soap box here yet. Just venting. Haven't been on the water. 60 deg end of next week. Maybe I should start using my boat packs to power my power chair. That way they'll be ready when the wx warms up.

Just a recommendation.......if your new with rc period, maybe go with NiMh (just a few packs and a charger that can handle lipos and li-ion too). Get the hang of the boat with the NiMh, because lipos will add 5-10mph on top of a good setup. With the "SV27.5" on lipos, she'll be zinging at 45+. Wrong setup and you'll need SONAR. You'll still be able to compete if you want with the NimH this year. If you want to upgrade to lipo, then you have the experience of running with others (learn from them too on what you need to do with lipos) and how to setup, and can gauge how sick you are with the FE disease.

We're already pushing the control envelope with NiMh on this hull anywho. OC has 42ish on chop with a 3-banger and I'm a knockin' with mid37 on dead water with a 2-banger. Ohhhhhh...... "I feel the need......the need for....."