Not to hijack this thread. With the lower watt Mesa (the Mark V 25 and 35 and the Rectoverbs) I see they tend to use the 84 tubes as opposed to the larger amps using the 34. I already own two amps that use the 84's, a Vox AC15 and and Orange Rocker 15. Should this affect the pick. Do the higher wattage amps sound that much better? Mind you, I am a 2 year experience home player so using high power heads is likely going to get me yelled at.
Here's the thing about amps and power: Different circuit designs can have the same power rating, and still be different in where the volume sweet spot is. Also, there are different methods of rating power in an amp - RMS power, "Peak" power, IHF power, etc. And different speakers react to power in unique ways due to efficiency, the amp's damping factor, etc.
So know in advance that sometimes power ratings aren't as meaningful as you might think. They're relative measurements with variables.
A big amp will usually have more clean headroom because of not only the power, but the larger power transformers, the tubes designed for more power, etc. It'll have different tone on the bottom end, usually tighter and more piano-like. It will be less likely to mush out. A lot of folks buy a 100W amp for that reason alone; one of my amps is a 100 Watt amp simply because it does its thing on the bottom that I sometimes need.
Another issue folks have a tough time getting their heads around is volume pot and gain pot taper. An amp that seems very loud quickly when turning up the volume is sometimes that way because the volume pot taper is quick, and before you hit the halfway point, the amp can be out of gas and not get any louder.
In general, an EL84 will feel a little squishier on the low end than an EL34 for whatever reason, unless some of the bass is filtered out, as with an AC30. AC30s (4xEL84) can get extremely loud. because the bass is the part that really taxes output power. The AC30 has a lot of midrange and high frequency, but the bass is cut. So it's not working as hard, and gets pretty darn loud.
Conversely, a 30 Watt Mesa amp can feel a lot quieter, because it reproduces a ton of low end. And pick attack varies among amps depending on how fast the amp responds to the transient attack of the pick. Slower amps are thought to be "forgiving," while faster amps are often called "stiff."
Then, too, there are 30 Watt EL34 amps, like some PRS HXDA models, the Bad Cat Hot Cat, and others.
BUT - the output tubes have less of an effect on the amp's tone than most people realize, because a lot of the action is in the preamp and tone stack.
So as you can see, there are infinite variables in all this, and the best and only way to really understand what's gonna work for you is to go out and play the amps.