No mate, I use 2 double VU+ cable tuners on 2 VU+ boxes and a sundtek cable tuner on another box all running at the same time i have no problems with them at all... the only time i have had problems is with crappy self applied ariel connectors (introducing noise into the system), only time any of my friends and family have had problems, is one had split their own signal and it wasn't locking, even though they was still getting internet on the modem on the other split, and another's cable had been pierced by a gripper rod and was leaking noise into the system... Noise is the big thing if you are not getting certain frequencies, it's the reason VM send you a silver cap when you have your services disconnected.
p.s. All my connections are VM installed tap points, no splitting and all cables are pro made with adaptor 's to convert from F - RF where needed and my snr is 99% on every frequency... if i insert one splitter i start to loose certain channels, and some start to go blocky.