I agree with this if you're swing trading or have a more short term mindset. At this point in time BTC is dominating the market, but once more fiat pairs come around then thinking in satoshi's may not be the best way to think.
For example, look at LTC. It's up twice as much as BTC in the past year in fiat, but before its big run it was down significantly against BTC.
Exactly - if you examine Litecoin compared to BTC, it was lagging for quite a while - months. It made huge gains in fiat the last couple days, but relative to where it stood against BTC before, it is not as huge of a gain as it seems to be. Many coins have consistently lost ground to Bitcoin over the last year, yet appear to be a great investment, when, in reality, the admittedly less exciting standard Bitcoin would have made better gains over time. Litecoin is a rare exception, mostly because of its recent run-up against BTC.