This is my multi range fire support. His main role on the battlefield is to supress the enemy so that your team is free to move and get into whatever position you like. The dual AC5s are great at shaking cockpits and laying supressing fire at choke points while the LRMs constantly trigger warning messages. Medium Lasers of course for the close quarter combat. Check out my tutorial video on the playstyle!
NO POINT IN USING AN XL275, XL280 weighs the same. Those LRM5 is not enough to do any real damage, and you don't even have BAP for LRM to boot. Basically useless unless you just want to grind kill assist. I suggest dropping those and maybe go for some SRM instead. or you can really focus on LRM + AC, but you will be slowish YES IV4 is not that good of a mech for what you are looking for.
Yeah you are right with th engine. I went for the XL 275 because I had that in stock and did not want to buy another reactor for the video. On the other things I disagree. This Mech is not designed for maximum damage but for maximum suppression - therefore I called this one "Sidekick" . Sometimes it is not about the numbers but about the playstyle and your strategy. Just watch the tutorial. There I explain why I chose the 2 LRM5 over something else.