Garmin 305 VS 310 XT

310xt if you want/need:

*Increased battery life (above ten hours)
*Ability to swim with the unit (although GPS and HR won't work while swimming)
*Ability to link with an ANT+ device like a power meter.
*To spend twice as much money to get the other functions.

GPS actually works pretty well in the water after a recent update (not perfect, but about 100x better than it was).

I don't know about the 305, but I have the 310xt and it is awesome!  It's a bit chunky, but I can't complain because it does everything but cook breakfast.  It's sturdy, battery lasts forever, and it is customizable to whatever data you wanna be looking at while working out.  Love it! 

What??!   Please elaborate.  has a firmware update made the 310 a true triathlon watch?

what are the sweet deals that you ahve seen for the 305... I am looking into that model as well

Post-update results I've seen have been mixed at best.As far as deals, Amazon usually is close to the lowest price, currently <$150.

In my opinion the battery life is the biggest difference between the two models. If you don't need the longer life of the 310xt, then you will be fine with the 305.

I don't know what you have seen but you can find a sub $330 310xt w/hrm on ebay.  yes, they are new.  Just ordered mine so can't speak to quality etc but I have yet to read a review buy an owner that was not very happy with their purchase.

I bought a Forerunner 305 about 1 month ago and think its excellet.  As a full package its good.  in the box is  HRM and Unit + USB charger and software.   I bought a bike mount, and that is pretty good too.  You can add a footpod and cadece sensor too - but they are a little pricey (and I already have a cadence monitor fitted to by Bike comp and a Nike + system on my IPOD Touch for running).

On the whole I like the 305 for ease of use and the fact you can fiddle with the displays for different sports so it shows you what you want.  3 screens to cycle through per sport is good - loads of data.

Its really motivated me to improve my pace using a base Heart Rate zone.  The software package syncs teh GPS data with Google Earth so you get a nice picture of where you have been.  Also, all the stats are easy to follow on the Training Centre programme, so you can see how you are getting on.

The wrist unit is a bit chunky, but thats okay.  And the HRM Strap is pretty comfy (although it can chaff when it starts to get damp from sweat.  I can only speak about the 305 - but for me its perfect.

Here's some detailed information about the new Openwater Swim mode.

In short, it's a bit of a mixed bag - but a good start in the right direction.

My main concern was getting the device swamped at some time, after reading the comments here I think the 310, although a bit on the pricey side is probably the better buy, I prefer to rather buy the top end stuff and then not buy again until it really falls to pieces. ...runs off to bedroom with a hammer looking for the piggy bank.....

Nashbar has the 310XT w/hr strap for $400. 25% off code "FRAMILY" (through July 14) brings it down to $300, then add the $50 rebate from Garmin to that (follow link from Nashbar). $250 is a lot easier on the pocketbook.

Yes, in my original review I covered that pretty in depth.  There's no change/reason to utilize OW swim mode in the swim cap (in fact, plenty of reasons not to).  The OW swim mode simply looks to establish a pattern based on a series of data points that it can determine to be reliable.  In the case of the swim cap, virtually all data points end up being considered reliable (sat accuracy is high), thus in effect, it's a wash.

In my OW swim tests, I used the FR305 as a baseline, with two other watches (310XT's) on either wrist in the differnet modes.  The Garmin Engineers said that was an effective baseline.

Hope this helps!