I have had an MI SP 18 inch ML handguard on my 24 inch .375 SOCOM for quite some time, and while I really like the handguard, it is designed for suppressor use and is a bit fat for my hands and looks a little pregnant on a relatively lightweight barrel. This is what it looks like on a twin .358 SOCOM.
A couple of days ago I got a G3 18 inch in and after Duracoating to FDE, I replaced the SP on the .375 with the G3 ML 18 inch. This shed some weight, about 3 ounces IIRC, feels better in my hands, and honestly, I think it looks better on a lighter weight barrel.
So, what to do with the spare SP 18 inch? I have a 24 inch 5.56 x 42 which is a heavy profile along with a heavy Magpul PRS stock and VLTOR bipod, so on went the larger SP. A much better looking fit IMO.
Whether or not you like long hand guards is a personal choice, so if you don't like the looks, move on, no need to comment. But for anyone who likes the looks of a longer forend when combined with a longer than normal barrel, the above pictures give you an idea of what it will look like on your build.