not necessarily. if it came down to $100 to upgrade to an IF or $100 to upgrade to a stone that is 0.01 to 0.05 carats larger, I'd pick the IF just for kicks. Both are imperceptible to the human eye, but an IF is more impressive on paper than a minute carat weight upgrade.
To use an analogy using HWZ terms since HWZ is predominantly an IT forum - If I have the budget to choose between 2133mhz RAM or 3200mhz RAM, the increase in clock speed does not translate much into real world performance, but I might buy 3200mhz RAM just for kicks if the price difference between the two sets of RAM wasn't much.
Btw, I have refrained from commenting too much on this 0.7 carat SI2 for under $3k. But let me just say, at the end of the day, there is a reason why this 0.7 carat SI2, which apparently looks like a 1 carat simply due to a tapered ring band, is under $3k. Is it a value buy? Sure it is, depending on what your criteria is. But on an apples to apples comparison, is it fair to say that it is better value for money compared to a similar sized diamond with HCA score < 1.4 and top notch light performance as determined by ASET scope examination? Both a Honda and a Lamborghini will get you from point A to point B, but you can't say the Honda is better value for money simply because it can accomplish that while being a mere fraction of the price of a Lamborghini. To do that would be equivalent to the VTEC fanboys saying exotic cars are shite because their modded Civic can do a faster quarter mile.
At the end of the day, what is good value for money depends on what your individual criteria is.
BTW, I agree fully with what LL1986 and teqrise have said on this topic.