The great thing about many SVHS decks are that they typically have some kind of noise reduction hardware built into them, making playback better. However, if you plan to capture any VHS sources, you really need to have a time base corrector (TBC). A TBC will realign the output signal (because VHS inherently degrades each time its played) to its proper parameters, giving you an even starting point for your preservation work. Occasionally, you can find a decent deal for professional edit decks with TBCs on the eBay or you can purchase a TBC separately. Two models that I highly recommend are AV Toolbox's AVT-8710 and Datavideo's TBC-1000.