I'm not quite sure I understand your list here.
Without wanting to sound rude, seems more like a list of figures you have. You say it fares well, what kind of lists are you coming up against? Because this is a very focused on expensive
HQs and expensive hard hitting Termies and Honour Guard. If I was up against this with Nids i'd love it. And I don't like playing Marines because of mixture of 2+s, 3+s and plenty of decent shooting.
You have no transport or long range weapons on the 5 man
Tac squads, or the Honour Guard, two expensive biker
HQs with no squad to go with. a small squad of either footsloggin or deepstriking
TH/
SS terminators. None of it really seems to fit together that well. Like Andram said, you're first problem is low on troops. Three squads is good, but three ten man squads is what you want really. If you really don't like Tacticals that much, they need something, a rhino, anything.
At 1500, you definitely don't want to be spending over 1/3 of your points on
HQ (well, you never want to really).
You have four Dreads, at the moment i'd start there. I assume a
MoTF still unlocks Dread as heavy support? (I haven't really read the codex properly

). And i'd build around them. Definitely don't take two 200+ point chapter masters. Well, I say definitely, it is apparently working for you so maybe you should. But I can't see how thats a good idea in most situations.
But yeah, build around the Dreads, tactical marines, scouts if you have any. Try and get a bike squad for your
HQ(s if you really have too). Try not to footslog Honour Guard, if they aren't in transport then I wouldn't bother. You could almost get two Devastator squads for the points cost of that 5 man squad.