bike trainer vs. garmin 305 opinions please...m

Depends on how you train. I have a CycleOps fluid trianer and a Garmin 305, and i can tell you I use the Garmin dozens of times more than the Trainer. But if you're not willing and able to ride outside the trainer would be invaluable.

Bottom line: which one would YOU get the most use out of.

If you already have the HR monitor (MIO), then you could get an inexpensive bike computer to measure distance, and cadence if you feel it is needed..... 

I just use the 'routes' function here on BT to map out and measure my ride distance-which will also provide the avg speed for the ride.

I have limited funds and would love the Garmin as well, but opted for a trainer instead - I can train when it is dark, raining heavily or even snowing, instead of 'measuring' a non-ride when it is dark, raining heavily, or even snowing ........

The trainer will improve your ability.  The Garmin will just measure your ability.

That said, if you won't ride the trainer, get the Garmin.

Are you willing to ride in any weather conditions?  I have a trainer, but honestly I hardly use it.  I only put about 20 hours on it this winter/spring, and only when we had so much snow on the ground the roads weren't even safe to drive on.  Other than that, I've toughed it out, bundled up, taped up my shoes, and rode outside.  There's no reason you can't ride your bike in bad weather, as long as you prepare for it, and dress appropriately.  (It's also not a bad idea to do anyway, since you never know what race day will bring).

That said, if time constraints or your local geography make it easier for you to ride inside rather than outside, you may find you get more benefit from the trainer.

I love my FR305.  I've thought about getting a cadence sensor for it, mostly to make my trainer rides more useful in terms of feedback.  I definitely use the Garmin more than the trainer, including the HR monitor, and could live without the trainer.

Re: the previous poster: a tool like a GPS watch can actually help you improve your ability too.  I use it for post-workout analysis (how hard did I really push myself?) and for dialing in run workouts at a certain pace.  I could probably pull that off without it, but it'd be a lot more work.  People that train in various HR zones also can use a tool like a Garmin to improve their ability.

I have a CycleOps Fluid trainer and a 305 and I'd give up the 305 long before I'd be willing to part with my trainer. 

CJ