At this point, I have Ber and Sur pegged to Ber being worth ~2.3 Sur. Most players will use common sense if they have a Sur that they will then trade for another one to make their Ber instead of turning it into Ists to trade for a Ber. But if Lo is worth more then Sur on the market, I think players should be aware of that.
Am I comfortable with 1 Sur =/= .5 Ber? I think that displays a limitation in the market. You can cube runes up, but you can't cube runes down. The demand for a 'component' part of the Ber (1 Lo = 1/4 Ber) is worth almost 1/2 of that Ber. So if you could break down the Ber into 4 Los, then this supply issue could be addressed - people would break down their Bers, create Los, cash them in for more Bers to break down - until the market's demand returns back to the real value. But you can't do that, so you get weird inverted curves like this. Honestly would be fascinating for an economist to study this
But yes, a Sur should always be worth 1/2 Ber in real value. I think this helps to highlight a limitation of trying to put static numbers on paper when it's a ever changing market. Plus a lot of things are connected to each other - like Ists per High Rune. If I change those values, then does that change the value of the Ist or the value of the High Rune? So first, try not to change things without proper justification. And second, you can't update this guide in real time without breaking other parts of it that aren't targeted. I just want to set things in place and then tweak them instead of overhauling the guide when the price of currency changes. It would suck to change everything to some new baseline and then just go back the next week and have to change everything again because that baseline changed. But when the users say, "Hey, this looks wrong, can you fix it?" - then I know it's time to get out the calculator and get to work.
Finally, the guide is just a guide. If you can use it, along with other sources, to make sure you get a good deal or price out your items fairly - that's my desire. The hardcore traders who are moving runes, torches, annis and GG items do not need this guide. I just want to make sure the casual player has a resource they can trust to get their arms around this extremely complicated market.