I am wondering if the 100-300mm is worth the extra $$$ vs the 45-200mm. I live in Costa Rica and just getting into this M43. I've ordered a 20mm and a 14-45 lens for my GF1. I'm wanting to get into shooting nature shots- birds, monkeys, sloths, etc. Sometimes it's kind of dark in the jungle- shady most of the time. So do you guys think it would be worth the extra money to buy the 100-300? Is the 100-300 too heavy to on the GF1 half days in the jungle? Can both be hand held for shooting or do I have to lug a tri-pod too? Thanks in advance for the great insights.