Well, it depends on how big of a purist and what type you are. As all the Forum Daddies would no doubt tell you, if your intended audience is to process truly raw wavs transferred at the exact speed, EQ and pre-emphasis the original artist and/or duplicator intended, then yes, your resulting wavs would in fact be somewhat colored.
Except every duplication-mastering engineer, every safety-master engineer and every duplicator-calibrationist in your original production chain will calibrate his gear slightly differently anyway, coloring the material in its' own way. So you may still be a few generations out of what is known as `true-spec' anyway by transferring 100% completely flat.
It's a call the trained expert restorationist or transcriptionist has to make from listening to the original material
However, if your eventual intent is restoration, it's a lot easier to put especially treble EQ back to where it belongs in the computer later. The exception MAY BE tapes mastered with Dolby. To get the best, most versatile transfer in the end upon which to best perform various processes, it may be necessary to SLIGHTLY re-calibrate the professional mastering Dolby Card (A, B, SR etc) the same as adjusting Rack Wrap Height and Azimuth prior to transfer.
Especially since the various noise-reduction and other algorithms like a lot of treble to work off of. Even in the case of LP's and especially CD-4 LP's and prewar and international 78's.
In the case of CD-4 LP's, to transfer without RIAA equalization preserves more of the top end upon which to better render click and pop removal, hiss removal and rumble removal later. The restorationist in this case may choose to apply his reverse RIAA EQ
after restoration for greater clarity. Of course he would need to label his `raw transfer' as `missing RIAA' so people would be aware.
In the case of prewar US and International 78's, there's so many turnover curves you almost
have to transfer flat with no EQ curve because so few phono preamps have every single turnover curve available, nevermind if the turnover has to be slightly adjusted manually. And the same thing, you'd have to label the transfer as `turnover not applied'.
And then in the case of disc, once Carl Haber's scanner is perfected
http://irene.lbl.gov/ then, at least all the problems of cartridge, preamp and other playback coloration will be solved due to an absence thereof. Technically the IRENE though was only for mono, lateral discs, and was just a stepping stone for the one in tryouts in Summer 2008. Based on a confocal high resolution microscope, the new machine can do lateral, vertical, both simultaneously, matrix. discrete and any other kind of LP you care to find.
So, again, it depends on how stringent and of what type the purist within the transcriptionist is.