And now I'm going to stop holding my tongue and say what I should have said - although sound is the top priority, there is NOTHING to lose from trusting mathematics if it's in its proper place and you know what to make of it. There is no arguing with mathematics, period, end of discussion, so when someone who knows it well comes along and figures out the ACTUAL DIFFERENCES between things it is FUCKING STUPID to ignore it unless you really love WASTING A LOT OF TIME AND MONEY. I have recommended the TS7 and SD-1 to many people who would not have tried them otherwise; to the best of my knowledge not one feels that s/he was steered wrong... rarely do people trust their ears with cheaper gear, though, because they want to be part of a fictitious elite few who can hear the difference between a $100 copy of a circuit and a $10 copy of a circuit - whether there is one or not - or between two copies of the same circuit made of the same components with two different brand stickers - whether they're discernible through a given rig or not. So, given that the circumstances necessary for truly trusting one's ears with tiny differences like these are well beyond convenient (blind tests of many pedals - including several of each make - through several rigs), there are MANY circumstances where trusting mathematics first (like finding differences between TS models) is the best option.
I'd like to know exactly where you got the impression that the TS models were so different, honestly... people love hearing differences that aren't there. It's too obscenely far from PS vs XBox vs GC for words, so that analogy is very poorly placed. Circuit analysis can tell you that... and save you tons of money by just redirecting you to the TS7 and, if necessary, the TS9->TS808 mod if you have a truly phenomenal setup.
Jeff