Cost not too much of an issue - I want this to be spot on and last "forever" - but keeping cost down is always welcome, regardless.
IMO -
1) having it be consistently smooth/flavorful while native... which from what I am reading, that is very possible with the right torch size/where you focus your flame etc.
2) having it be easy to clean as possible (maybe more so: with as little frequency as possible).
1) What you are reading is correct, once you dial in the flame size and where you are aiming it (minus any environmental factors), it will hit consistently like that from my experience. This is the true beauty of the anvil, no guessing games, just perfect hits to YOUR preference! It is what finally got me away from combustion after trying a few other solutions.
My go-to late night hit is a Ronxs torch, inner blue flame the length of the oven, pointed right at the bottom edge of the thermal battery until both clicks. This one doesn't preserve the flavour as much, but will kick your ass.
For more flavourful hits, I aim for the middle of the oven while dialing the flame size down just a notch. Then you can finish it off with a second heat cycle if you are greedy like me, just be careful to not overheat it when the herb is already half vaped, it is more susceptible to combustion in that drier state but as long as you keep the flame size under control and don't go over the click you won't combust.
2) I clean my anvils once a week with an ISO bath and qtips, but I feel like that is not necessary. The design of the anvil allows reclaim to flow through the device and sometimes out of the bottom of the mouthpiece, a quick q tip/rinse of that reclaim in the mouthpiece is really all it needs to keep chugging, the screens never clog unless you over fill the bowl. IMO - This is one of the simplest vapes to maintain. I knew someone who ran the anvil for months and months on end daily with no cleaning and it was still ripping.
do I just buy the full default setup + XL mouthpiece?
Or do I buy just the oven+USA
If cost is no issue, I do see benefit in owning both (I own both). They both offer "different" experiences. Both will last on this earth longer than me so I figure the "forever" requirement won't be a problem
The native setup provides the perfect cigar/joint like puffing experience with the XL mouthpiece for MTL puffs. It can and will still rip in one long draw, but...
The USA provides better airflow making large lung busting single hit extractions easier on the lungs, but the MTL hits feel less satisfying than on the native anvil.
Save yourself the VAS and shipping and get both
I would even say that once you try it you may want another oven to stop having to swap between them like I did but perhaps that is a little overboard
Edit: on the go.. the Vestratto travel case will be your best friend. Its a good place to store the hot anvil safely while its cooling down while camping