hmm... "The important thing is the relative movement of the altcoin to bitcoin, i.e xvg/btc pair analysis." Consider this other perspective: If you were to get your salary paid in btc and you paid for all your goods and services in btc (and those had a stable price), or if you are never going to sell your btc because you feel that in the future it will happen, then I guess you might think that btc pair is more important than fiat pair.
I have been using btc pair for analysis for months but I now understand (thanks to the recent BTC correction) that this is not the right way to look at it and only makes my gain and loss 100% dependent on the BTC highs and lows.
If one analyses a trade against fiat then their gain and losses are effective.
One still uses btc to buy and sell but if you decide to not hold more than a given % of your portfolio in btc and keep another % of cash on the exchange to enter new trades when opportunity arises, then you are surely taking less risk. This is at least the way I am looking at it now and I am still to implement it when I will be ready to see the coins I am holding...