Does a 1/2" immersion chiller really work better than 3/8"?

39.69 for 50 feet of 3/8" copper tubing on coppertubingsales.com. The 1/2" is $49.99. Is it worth the extra $10 to get the 1/2"? Does it speed up the wort cooling time at all? I watched Bobby M's video and I don't really feel like boring out the garden fittings to make it fit 1/2", it seems like 3/8" would work better in that regard. Any comments?

I only need a wort chiller now and then I'll have everything necessary to brew all grain!!!!

Well, 50' of 3/8" copper gives you 0.456m^2 of surface area.
50' of 1/2" gives you 0.608m^ of surface area (sorry I'm used to the metric system). Or 33% more surface area for the same length.

As to whether it changes cooling times significantly, I have no clue.

the simple answer is yes.
I upgraded to 1/2 and it cut my cooling time in half.
$10 well spend IMHO

I bought the 3/8" from Coppertubingsales and ended up just buying a bender and soldiered on some garden hose fittings and some stiffening points, I am proud of it, and it works great, I get from 212* down to 65* in about 5-6 minutes.

If I had the chance to do it again I would buy the 1/2", looks better, stiffer when built right, and will be better when I graduate out of 5 gallon batches and start doing 10+ gallon boils. bobby's video makes building it easy as well.