Yep, I have both GPS Map 60 and a 60cx, the former with the old SiRF and the latter with SiRF III. It's much better at picking up signals in poor conditions. The newer unit can be carried in a rucksack or bag and still work; the older one couldn't so I had to wear it around my neck. Even then it was shielded by my body.

I don't think there's much difference in accuracy, though. The new one usually claims around 12-15ft. It's enabled for WAAS/EGNOS but in practice I rarely get a signal from those satellites where I live.

There may be a difference in acquisition speed but it's pretty nominal if both have good signals. The newer model does show satellite IDs almost immediately (which I think means it has recognised their signature and so has the right frequency and phase), but then you have to wait for the ephemeris to download, which can still take a minute or so. It's mostly luck how long it takes, depending on where in the cycle the broadcast is when you switch it on. Time to first lock is longer if the device is moving or if it's not been used for a few months, which may affect naive comparisons.

The extra sensitivity is a huge improvement regardless. As is having upgradable memory (I have a 2 Gig chip with topographic maps for my entire country) and various other changes.