I will do that (here entry level imac 5k costs 2400€ which is about 2750$- so options are pretty scarce) . I wanted to know experiences of people who have their macs 5+ years.
I used to have the old G4 MDD for 5+ years, and now I have the MP5.1 for 5+ years. Having said that, I did not have an iMac so far. My good old MacBook Pro is 8 years old now and as a good as new on its first day.
My dad has a Mac mini from 2009, reaching the full decade next year.
In retrospect, I think Apple hardware used to be solid. However, proper cooling and heat is always important to watch. If you game the hell out of it on a consumer mac, your hardware will die a lot sooner for sure. Also, Apple hardware changes a lot the last decade. Today almost no computer can be upgraded any more.
If this computer is a long-term item that you want to keep, you need to ask yourself the following question: How tough will you tax your system for how long and how important is it to you to have the latest and greatest hardware.
The iMac targets semi-pro individuals and consumers that are willing to use the system for about 5 years and then replace it like an old electrical shaving device. An iMac is an appliance with a designed live cycle in mind. Chances are high that electrical components will die soon after a projected age. Often because of heat, dust and the inability to upgrade. Buying an appliance, "they" already took away any possibility to upgrade the product to force that renew-cycle on you. It needs to be sexy otherwise you would not buy it, but it will die on you. In the Product live cycle Management classes, they call it programmed product obsolescence to ensure a constant stream of cash flow for the company.
If not, you need to look for a system that can be expanded and upgraded over time. A system that keeps its value for a very long time. One, that has a very well thought out thermodynamic design that will last for decades or longer. Apple care is complete nonsense because it only covers Apple's Six Sigma failures/problems in the first couple years, but it will not really help you to prolong you systems live cycle. (Apple care package for the 7. 8. & 10. year of usage- anyone
??!!) of course not...
My recommendation:
The new iMac will hit the floor very soon, that means prices or current and slightly used computers will drop!
Wait till the new iMac has been introduced and watch prices drops. There will be news on the new Mac Pro 7.1 as well.
Do not buy any new/used computer before November. Unfortunately, it is too late for the golden cMP 5.1 game at this time. The MP 6.1 would have been so-so, but very expensive, bad heat design, failing Apple GPU's, no GPU upgrades and last but not least a
"from Apple gimped/deleted eGPU support" that will make you furious like hell. Can't innovate anymore my ass, - Thank you Phill for this non-upgradable BS... but hey .. it looks nice.
If you are a real professional in the way that you need to make money from your investment, go for HP800Z or a good Render Monster machine like the MacRumors member Tesselator. Pro is not always pro. If you just do some light photoshop, Adobe stuff without big existential pressure and your computer is not part of a tricked out Tax deduction game inside your legal entity, you might be fine with an iMac, otherwise, wait for the new Mac Pro 7.1. This, and a good airconditioning fed by solar panels, subsidized by your state tax dollars...