I would have to say that EAR amps are about as close to bullet-proof as tube amps can be. The parts quality is not great, but the components are designed to run for a long time without tube replacement, and if there is a failure, that it can be repaired in the field relatively easily (remember, TdP designs for the studio too, where gear has to be reliable and easily repairable). A competent / qualified tech will not have to struggle with a piece of EAR kit.
Another thing I like about gear is that it is not too tweaky (I believe all of the modern EAR gear has self-biasing circuits), and most if not all amps have 4 ohm and 8 ohm taps which is a nice touch. My favorite part of EAR amps though is the volume pots on the inputs so you can bypass a pre-amp.
Here are the drawbacks to buying / owning EAR gear (assuming you live in the USA):
1. Should you have some extreme failure, the gear would potentially have to back to the UK. This has never happened to any of my EAR components, but anytime that I buy any European or Japanese manufactured gear, I always keep that reality in mind.
2. Any and all EAR dealers are likely to be smaller outfits. This may sound like a generalization (and I apologize for the slight to any EAR dealers that have huge stores with lots of employees), but the EAR dealers I know are either home-based or have smaller stores. The Distributor (Dan Meinwald) is a very nice guy that participates in industry events and has been the EAR distributor for a while, so it is a not a hot-potato line that switches distributors ever 2-4 years.
But with all those things said, should you have a problem with the gear that requires serious surgery, you have to go through a dealer (who may be a one-man show), who then goes through a distributor (that is a one-man show). If all your stars are aligned then all these guys are home and return your call right away. If everything goes wrong, you have a couple days turnaround per gentleman. So the risk is that your system can be down for longer than you would like it to be (or longer than it should be).
3. Tim de Paravicini may be a brilliant designer but from what I understand, he is very protective of his designs and any criticism of them may result in him flying off the handle on you. I think we all understand that this is an issue of personality rather than product, but c'mon, I think all of our music collections would be a lot smaller if we only bought music by artists that were nice to everybody.
So those are three drawbacks that I can think of to owning EAR gear. Fortunately, none of them apply to me. Why? I'll tell you:
1. I've never had an EAR component fail on me, so I've never had to ship it off anywhere. Tubes have burned out of course, but I do not consider that a failure.
2. I have a competent tech within a 1-hour drive that is qualified to work on EAR gear. I'm sure if you emailed the EAR distributor, he would ask you where you are located and then tell you the nearest competent tech that he would trust to work on an EAR component.
3. I generally find the colorful personalities in hobbyist audio pretty entertaining and only sometimes insulting or a pain in the butt. I've talked to or met my fair share of designers, and although I've only found one of them to be difficult, and that designer was not Tim de Paravicini.
If you've read this far I have a few other things to say, but I caution the reader that these are all anecdotal experiences, so please take them as such:
* I love my EAR gear but it is expensive (and this has really gotten bad in the last 5 years). I blame this on the weakness of the American dollar vs. the British pound sterling.
* I've waited a few days for responses from manufacturers with great reputations. This is a hobby, and they run a business, and if you mix the two, more often than not you do not get 4 Seasons or Ritz Carlton service. Hopefully you get great service, but as I said earlier, these are usually small operations with guys that are backed up, on vacation, or just dont recognize that you're their #1 customer. There are plenty of hobbyists out there that buy products that have a hot review but the business may just be getting started, so buyer beware.
* I contacted EAR in England directly via email one time. I had a technical question and Tim himself responded. He was curt, but he answered the question. It would have been nice if he had offered a salutation at least, but I was looking for an answer, not a friend. You cant ask for more than that.
Finally, I would just like to say that from a performance perspective, EAR gear is at the top. For what it is worth, I completely endorse the components. Reliability is top-notch and sound quality is some of the best out there.
I hope this info helps.