you are missing that the ships u call "advanced" have just different strengths.
Missle ships for example are not the best choice to fight light frigate, they are better suited to kill caps.
Every ship has its role and light frigates are a good unit for a long time and i quite like that.
The ships in Sins dont get obosolete just because u research more and more. Though the Heavy Cruiser does replace the Light frigate later in the game but even then they are a cheap and fast to build alternative.

I think what you are missing is that you will need a fair number of ships escorting your cap ship. If he's spamming 20 light frigates and sending them at you, you will normally need a similar-sized fleet, give or take, if you are talking the same class of ships (you could of course use less numbers of higher-classed ships, I'm guessing).

Pay attention to unit matchups, too. I'm by no means no expert on this game at this point, but in my last game I did build a carrier cap ship, and when I went into a system that had enemy flak ships, I made sure to take those out first with my light frigates, my assumption being that once those were taken care of, my bombers would be free to do damage without much of a counter. Seemed to work.

This game just takes a little getting used to is all. My first game I got owned by 2 AIs crashing in on my system together at the same time. My second and third game I'm doing much better.

Hey thanks for the advice...is any of this stuff (i.e. frigates are good against X, not Y) written down anywhere? I have the digital download so I haven't seen a manual or anything.

The problem with the orbital guns is the tactical limitations...I always seem to be running out of tactical spots for a single planet.

SoaSE is different in that the early non-capital units available only really have one standard "fighting" unit: the light frigate. Flak Frigates, Siege Frigates, Colony Frigates, and Scout Frigates don't really stand a chance against a Light Frigate in a standing fight. LRM Frigates can do quite a bit of damage, but are intended for fire support rather than slugging it out (i.e. they can dish it out, but can't take it).

Even most of the cruisers aren't particularly good at I-punch-you-punch combat, the only exception (iirc) being the heavy cruiser which is essentially a really big light frigate

So, unlike a lot of RTS/4X games, you don't have a ton of units to choose from for the "front line inexpensive fighter" role; you've got the light frigate. So build lots of them early on

At least that's what I've seen, I could be wrong.

Edit: the manual.pdf file is in your installation directory (usually under program files/stardock/...)

I don't really like the defensive guns due to their very short range, so unless you clump them to gather only one or so will actually be firing on a target. But if they are clumped together then they can be avoided completely.

I prefer the hangers much more, I usually build 4 of them with 7 bombers and 1 fighter. If the system is a on the front lines I will also have some light carriers and some basic attack frigs. If you can get around 15-20 bombers in one system they can put some serious hurt in an hostile assault, especially if you micro the bombers and get them to all attack the same target. With 15-20 bombers all attacking a frig they can usually pop it on their first fly by.

For secure systems that cannot be directly accessed without going through one of the front line systems I just stick with the 7 bombers and one fighter.

For a choke point system if you can get 30 bombers and put them into two different groups and have them target the hostile frigs, the rest of your fleet can attack the cap ships and cruisers.

The only thing you need to watch out for is a swarm of fighters or lots of flak ships, the best way to deal with this is to dock all your bombers and have your support fleet take care of the fighters and flak ships. So make sure you have at least a couple flak frigs in your fleet to stop fighters. Once most of the the anti-bomber ships are dead relaunch your bombers and finish up the fight.

Gauss cannons are weak, they are supposed to be.

You have to build alot of them to be effective, at the very least, eight.

They should be backed up by at least two hangers and two repair bays, if you do that, you have a basic defence going.

Note: it is unwise to build just Hangers, which don't have the fire power, or just gauss defence, which don't have the range. You need BOTH to have a proper defence. the Gauss protecting your planet and your buildings, and the hanger attacking stuff outside of the guass range.

Unfortunately, frigates quickly make me reach the fleet cap. Fighter hangars and gauss guns are awesome planet defenses when you're trying not to level up your fleet caps too quickly to avoid paying increased fleet costs.