While I am not as hard line about no XL in assault mechs as some, I do think for your build a standard would be a better choice. The only time I can see an XL being worth it in assault mechs are for sniper or LRM builds that never want to get close, or close range bruisers that never ever go in first. But for an all-purpose/all-ranged build like this, I think a standard engine is well worth it. Otherwise, I like this build. I'm a fan of more balanced builds in general, at least for pugs (which I do almost exclusively).
