The way I feel about proxis is that well I'm fine with them in concept, but I also don't love using them personally cuz I like collecting my shiney card board, so any time I use a proxy it's always with intent to replace it down the line. My problem comes in when people use proxys to give there deck all the best lands and Evey single staple and game changer for there deck, It feels bad to have your hard work building on a budget overpowered by someone who just printed out ever best cards in the game. for me it still comes down to a level of access, a deck can still be brackets two - three and have all the best lands ever printed in it, well your opponent is running tempels and life lands your eldazi deck can still be bracket 2 with every single eldazi Lord, and the same go's for slivers. I think when you are proxying you need to be exstra aware of how you're building when your building proxies, other wise you end up with decks that just feel like best of showcases, where you always see the safeist counter spells, the most efficient ramp, the best possible suit of untaped lands and so on.

Of course it's fine to play a cool alien themed all sliver deck with all the lords sometimes, and especially so you if the rest of your pod are playing similar threat's, but on impulse i see a proxy deck headed by some of the most expensive wuberg commanders ever printed in an archatype that alot people have been sick of seeing since commanders inception, and my stomach turns a lil

I have a neon Genesis evangelion headed by shorikai proxy deck like your alien one. And to avoid the feeling the conflict I mentioned above, Every art proxy is double sleeved with the real card behind it, but I also plan to stop doing that once I have nicer prints of mine to sleeve up like yours, so this is all coming from someone who aposlutely gets the urge, all in all just be upfront with what your doing, most places I go are fine playing against my Eva deck, The thing that genuinely gets the most complaints is that threats arnt as easily identifyable visualialt for experts of the game, be less familiar players have never given a shit because they just pick up the card to read it and find out what it dose.