Um, okay, check me on this, but it seems like you're saying that the two of you are discussing whether
"1 elite monster = 1 PC"
but one of you is thinking "=" means "is the same as" while the other thinks "=" means "is a good match in a winnable combat for" which are two very different things.
So, uh, there's your problem.
As for the other question, according to 3.5 rules one NPC with equivalent levels in a PC class is considered a standard challenge for a party of 4, because CR=ECL for class levels. (barring the "associated class" weirdness of powerful monsters that also have class levels) So that would mean that under 3.5 balance, a PC would equal a Solo monster. It does look like, with the new focus on group combat in 4e, maybe Elites would be a better match, but it's hard to say for sure.
"1 elite monster = 1 PC"
but one of you is thinking "=" means "is the same as" while the other thinks "=" means "is a good match in a winnable combat for" which are two very different things.
So, uh, there's your problem.
As for the other question, according to 3.5 rules one NPC with equivalent levels in a PC class is considered a standard challenge for a party of 4, because CR=ECL for class levels. (barring the "associated class" weirdness of powerful monsters that also have class levels) So that would mean that under 3.5 balance, a PC would equal a Solo monster. It does look like, with the new focus on group combat in 4e, maybe Elites would be a better match, but it's hard to say for sure.