It's pretty easy to go from methadone to buprenorphine/Suboxone/Subutex, it just requires one wait a little longer than going from another full agonist that isn't as long acting to it. Most medical professionals, ESPECIALLY in clinic settings (where the general state of medical knowledge is extremely impoverished), have an extremely poor knowledge of what methadone and buprenorphine/Suboxone do, not to mention how they actually work (and prescribing doctors generally aren't much better). The extent of most professionals' knowledge when it comes to methadone (in the US) is from legal and bureaucratic guidelines surrounding it. When it comes to buprenorphine it's even worse, most of what they know is a product of pharm sales reps and their companies. Neither source is known for the transparent public dissemination of accurate medical information.
A side note before I continue: the naloxone in Suboxone essentially does nothing. For some people its addition in the medication leads to side effects. For the rest of us it essentially doesn't do anything. Its oral and sublingual BA is so low it doesn't get into one's system for all intensive purposes when you take the medication properly. It was only added to help it get approved by the FDA for the treatment of addiction in a primary care office setting (as opposed to a clinic setting like methadone). The idea is thrown around my its manufacturers, sales reps, and consequently doctors who prescribe it, that the naloxone will "block" or prevent the misuse of Suboxone and keep people from taking it intranasal, IM or IV.
However the naloxone still has essentially no practical effect when taken intranasal/IM/IV. In the case that the ROA has a high enough BA for the drug to actually get into your system, buprenorphine significantly outcompetes naloxone in terms of binding affinity (this is where opioid receptors come into play). For the same reason, because buprenorphine has a much higher binding affinity than almost any other opioid (certainly all commonly/normally misused ones), it will prevent those other opioids from binding to the opioid receptor systems if buprenorphine is already in the system OR cause precipitated withdrawal if an individual already has opioids in their system by knocking the previously taken opioids off the body's opioid receptors, causing a very intense, short lived withdrawal effect.
Methadone's "blockade" effects are de facto similar to this, in that it will prevent one from getting high off other opioids due to the opioid receptor systems being flooded with methadone, which has a higher affinity at higher concentrations than most other opioids as well, but the blockade effect of methadone is totally dose dependent where as with buprenorphine it is not (it's easy to get high on other opioids when taking lower doses of methadone whereas it's more difficult to get high on other opioids when taking lower doses of buprenorphine - a little bupe produces the same kind of blockade effect that a little methadone will not).
Precipitated withdrawal has nothing to do with naloxone when it comes to Suboxone. The reason some people emphasis you should wait ridiculously long periods of time when switching from methadone to buprenoprhine is because, when taken at really high doses (60mg or more) and for long periods of time (six months or more) the dose of methadone has build up in your system such that for some people it actually takes about five days for the methadone withdrawals to even begin. Now, the vast majority of people don't need to wait that long for methadone withdrawal to begin. But if you were taking a high dose or oxycodone for long long periods of time, you'd also have to wait much longer than if you'd just been taking a few Percocets every day for the last couple months. Same deal.
Also, medical providers like to make opioid addicts suffer, and I believe this does come into play. Plus precipitated withdrawal will happen at different times given different people and different circumstances such that it would be difficult for a medical professional to say, "Okay at X amount of hours you'll be okay to go," instead of the much easier, much more generalized guideline that is based on the logic that no one should have to wait longer than Y time so that is going to be the baseline applied to all inductees.
But anyways I'm going a little far afield. I'm definitely going to (probably

) use buprenorphine in my detox arsenal when I come off methadone, well if I need to I mean. I don't like the idea of jumping back and forth between buprenorphine and methadone really quickly, but not so much for any other reasons than that it will mess with the tolerance to each drug in major ways, fucking up their relative effectiveness. Generally it's much better for one to stick to one or the other. Switching from one to the other isn't hard at all for the vast majority when not totally fucked up by bad medical professionals, and shouldn't involve any serious suffering - even the more nuanced switch from methadone to buprenorphine.