This is going to vary from customer to customer.
I have customers that have replaced wiring several times, it started in the Cat3 days (even have a few that demanded Cat4 during that window) then Cat5, then Cat5e and now Cat6. For the most part, they are all still on 100 mbs ethernet. For the most part, they wasted quite a bit of money.
On each upgrade, I asked the same question, why do you want to change? The answer was usually 'because there is something better'. Being from the old school for the most part, I learned that the customer is always right (usually). My role is to provide the customer with accurate information, education and solutions and let them select which ones to invest THEIR money in. It is not my role to choose for them, but to guide them through the process.
If the customer calls and wants me to 'upgrade' their network, I'm listening because that is my role. If I present the pros and cons to them and they determine that they want a better product even though they may not use it for awhile, then I'm happy to provide that. I feel I can sleep at night knowing that they made an informed choice and I'm not selling them a bunch of crap.
I've turned down jobs going the other way however, where the customer wanted a new place wired with Cat3 for example. In the long run for me, it's not worth putting my name on a substandard installation because sooner or later someone will say 'Ah, I see who did this shoddy work".
Most customers I've dealt with like the options to choose from. I can't agree with Doug that all customers are going to appreciate getting a more expensive standards compliant system ready for growth. In my market, being $2k cheaper for a Cat5e vs a Cat6 installation gets me the job almost every time. Much like buying a PC, if you go get the bestest one right now, next year you'll be upgrading video cards and the like our technology is changing vary rapidly.
We really need to look at the history a bit and ask our selves what the actual usable life of a structured cabling system is. A few short years ago it wasa Cat5, that was going to do everything for us, we did everything with Cat5 and the customer thought that would cover them forever. Here we are now and it's not even standards compliant. For those that were really concerned we ran multimode fiber. Surely that would cover everything they needed. Now we find that we may need a different grade of mulitmode or maybe 50 micron to meet some specific speed and specs. SO, I suggest carefully weighing what we install, there is a cost break at some point, and maybe it's better to install a 5 year type system, planning on upgrading to the new Cat84 or whatever when it comes out in 5 years and be current then.
In new construction I am much more concerned with pathways and raceways. A well designed installation has raceways in place that allow a rather painless upgrade. Because, folks, we are going to upgrade at some point. And when we do, having the raceways in place to do so is critical.
In summary, I think it is our role as engineers, designers, and installers to provide the customer with the most cost effective solution for the current and future needs. Almost all the customers can tell us their current needs, almost none of them can tell us their future needs. My general recommendation is to provide raceways for the cabling, and provide the customer with a couple options starting at minimally standards compliant and ending up with a 'futureproof' proposal.
Good Luck!
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com