Clonazepam and methylphenidate together are very different than say Dexamyl (dextroamphetamine + amobarbital), and very different than the opiates you mentioned (hydrocodone and oxycodone). Let me first start by explaining that methylphenidate and amphetamines are just not similar, really. Methylphenidate has a different mechanism of action, is much shorter in half-life and duration of action, and exerts different effects on the body and mind than amphetamines do. Methylphenidate is rather like cocaine in structure and in effect, although it lasts considerably longer than cocaine and is commonly taken orally. However, compared to amphetamines, methylphenidate's half-life and duration of action is much shorter. The effect of methylphenidate is different than that of amphetamines in a number of ways. Most who have used both will report that they prefer amphetamines for therapeutic and recreational purposes, and that amphetamines are easier to work with than methylphenidate. Methylphenidate's crash is swift and quite dysphoric whereas the crash from amphetamines lasts longer, and while it can be rather dysphoric, does not leave one immediately exhausted after the drug wears off. Amphetamines' effects taper off more than methylphenidate's effects which tend to just drop off. For me, methylphenidate seems to have provided more physical stimulation with less cognitive stimulation than amphetamines, and with amphetamines the mood-lift seems much more genuine and less "chemical". That is just a brief little explanation on how those two drugs differ, but the subject could be, and I am sure has been, discussed at great length.
Clonazepam is a benzodiazepine, not a barbiturate like amobarbital which was found in Dexamyl. Both benzos and barbs have good sedative properties, but most who have tried both will say that they far prefer barbs with a short or intermediate half-life like amobabrital than benzos in terms of "fun". It is generally accepted that barbs are euphoric drugs, and that benzos are not classically euphoric, but can provide some with subjective feelings of euphoria. Both are relaxing, and both are sedating. Both can provide good anxiety relief and mood-lift, but barbs are generally held much higher on the ladder of downers than benzos in terms of "fun".
So, comparing a clonazepam + methylphenidate combo and a dextroamphetamine + amobarbital combo can be hard esp. since when mixing stims and sedative-hypnotics, there is a synergy of sorts. I would guess that dextroamphetamine + amobarbital would be much smoother and relaxing, much more euphoric, and generally much more preferable to clonazepam + methylphenidate. However, that is not to say a good time cannot be had or therapeutic effects cannot be achieved with a combination of clonazepam + methylphenidate because they can. Adding a benzo to methylphenidate would much ease some of the physical effects of methylphenidate, help with the crash, provide anxiety-relief from the methylphenidate, and smooth it out, in general. Clonazepam is a good benzo because of it has a nice long half-life and works well all around, so I can see how it would help.
When you start talking about opiates like hydrocodone (Vicodin) or oxycodone (Percocet, OxyContin), that is entirely different. Opiates are truly in their own class, and everyone responds to them differently. They are fairly subtle, while retaining the ability to be incredibly euphoric. They ease emotional or physical pain, and are very relaxing, but can be stimulating, too. Opiate energy is very common for those using opiates because they do provide a sort of physical and mental energy and increase the ability to do work, and make the most mundane work seem pleasant. They do so much, and I cannot compare them to the clonazpeam + methylphenidate combo or the dextroamphetamine + amobarbital combo, because they are just so different from any of those drugs.
![:\](https://bluelight.org/xf/BL_Images/Orig_Emoji/wrygrin.gif "wry grin :\")
but I found that when I was prescribed Dexedrine IR, taking it with my prescribed clonazepam worked quite nicely. You ended up getting stimulation, but it wasn't excessive, nor did you get excessively sedated. Basically, you felt relaxed, yet focused and alert. It was a highly effective combination and I guess the modern-day equivalent of Dexamyl 
. Dextroamphetamine and diazepam also works quite nicely as well.