Hey Bromeo,
A couple of things I've noticed about your list first off is that the points don't seem to add up right. Here's what I noticed:
1. Your Tactical Squads should come out to 190 points each (170 base, 10 points for Lascannon, 10 points for Combi-Weapon), for a total of 570. Also, the TL Assault Cannon is a 35 point upgrade, which will make both Razorbacks 170 points.
2. Your Land Speeder should be 60 points, if you're only switching out the Heavy Bolter for the MM. Although I would recommend you add a HF to what you have already, if don't have the points (or the sprue) for it, that's not a huge issue.
To comment further on what Ben and Dissimulation said, games can be indeed won as a result of deployment. As a Space Marine player, your models and units tend to be more expensive and point intensive than most other non-MEQ armies. As such, you should try to keep them more concentrated to a well fortified area of the table if you can. You can probably do this in any non-Dawn of War game, depending on terrain layout. Dissimulation had the right idea in keeping his forces closer to together, and while I don't know what army he plays (My guess is Tau, but that's just a hunch...
), if he's playing a point intensive army against an MEQ list, he would probably have a strategic advantage with his playing style.
As for your unit load outs, having Flamers is fine, but you probably want at least 1 Meltagun in 1 squad. Lascannons are good too, but like Dave is saying, you should Combat Squad the units (and from taking Razorbacks, I'm guessing that you probably are. But if you're not, then the Lascannons aren't necessary). I've personally never liked taking Combi-Weapons on my Tact Sgt's, but they seem to work for some people. I prefer taking Power Weapons/Fists, but if you find Combi-Weapons working better for you, stick with them.
Your Librarian doesn't need a Combi-Melta either. Not that it is unnecessary, but you can probably make better use of 15 points.
Devastator Squads are a lot of fun to use, but are very overpriced. If you run them again, I would recommend you max out the squad to the full 10 man unit. You've obviously experienced what failing their morale check can result it, and with a bigger unit, you have better odds of surviving, and you won't need to allocate wounds to ML carrying models as soon. Also, I don't know how you typically decide which mission to play, but if you play all 3 types, you should consider getting them a Rhino. Otherwise every DOW game you play, these guys will be even less effective and only that much more of a point sink.
Dreadnought is fine the way he is. Put him somewhere where he can have cover and sight of the majority of the board if you can, otherwise just keep him in cover until something comes within sight that isn't far from one turns Movement phase.
I know it might be difficult to take all of this in without seeing it on the tabletop first hand, but I'm sure you'll get the hang of it. And it seems like you have a few people who are willing to help you out. Good luck!
