Guys, I think people have been on autopilot during this thread. Reading 3 words per line and then just reading the last post. Let's look at what the OP ACTUALLY wants to do.
He has 4 TQ440's and 4.. subs.
The TQ440 are a heavy box at 30kg but they make up for it in volume and sound quality. They're a 137dB box. Let's say that again. 137dB. That's 2dB louder than a W8, that weighs 90kg. They're louder than pretty much most boxes on sticks out there. I can only think of 1 box on stick that is louder and that's a Q7. by 1dB, though it has the weight advantage of being 8kg lighter..... bloody Germans.
They are alot to carry. The OP I can GUARANTEE doesn't want to be carting C7 (which is no bloody louder per box) about that's as near as matters twice the weight, twice the physical volume and ground stack only. (edit : ground stack only as an option for this system for the OP..... I know the box itself isn't)
Q7 is a good alternative as it cuts down on weight, yet retains the volume and pole mountability. But it's expensive new and rare (and still expensive) second hand.
C7 is more directional than the TQ440. On paper in it's basic form it isn't, but in practise as its fully horn loaded, it's dispersion figure is true down to a lower frequency. It also screams at you like a cat that's being repeatedly attacked by a bloke with a rasp before you hammer out half of your eq. (Please note once you've done this it does sound very good, but loses a fair bit of it's efficiency and is therefore actually a quieter box than the TQ440 if you want it to sound nice). The TQ440 has it's own settings for your processor and sounds fine with or without them depending on your taste.
Sorry, I've not heard the TT series stuff yet, when work calms down I'm going to arrange a demo (Thanks for the info a little while back Greg, I assure you I'll get round to it) but sadly on paper, they don't match the performance of the TQ440. Nor does anything from KV2, I'll repeat that I've yet to hear a good sound from a KV2 box but due to their popularity and good reviews from trusted people on here and elsewhere I'm putting it down to setup / operator error and I'm sure they're perfectly adequate boxes.
C4......oh come on.... Double the number of boxes, lose all your bottom end unless you put B2's under aswell. Need a truck to carry them. And have to live in the truck after selling your house to buy them.
So, what do I think?
I think that you're going to struggle with this one. If you use a van, flightcase the 440's in pairs. I take it you have wheels on your subs already. You can push 2 subs together.
I think the issue is the coverage more than anything. 1 440 per side positioned correctly is enough to cover 700 people without breaking a sweat, you'll only need a few watts per section per box to do this. But of course, if you have a wide room, this is where you need your second pair. Have you considered flying yokes? YES, it adds weight, and they're a pain to get on a stand but if you have big stands (say 3.5m max height or more) then you can get them right up in the skies and point them down. I've covered 2500 with 1 445 (newer version but same specs) per side. Have you considered smaller in / outfills. TQ310's, NuQ range? Remember, flight case the boxes in pairs and alot of venues, you only take a pair in.
If I can't persuade you to keep them by telling you you won't get much better without comprising either size, number of boxes, weight or your mortgage payments or all of the above (which is what you are trying to get away from if anything) then let me know and I too will be interested in the 440's. Either a pair or all 4.
So.... SUBS. TQ425's....... you're going to be fighting me for all the 425's in the country going second hand for quite some time. They're like something you're unlikely to get from a rocking horse. Damn good subs though. If you find any I can't recommend them enough. If you (or anyone else) finds any more than they need themselves PLEASE let me know. The problem is output. They're LOUD, they're LOW, they're LIGHTWEIGHT. What could be better? The problem is you STILL can't get one to keep up with a TQ440. A regular setup for me is 1 TQ445 and 2 TSW718 per side and the subs run out of steam before the TQ445 does. The TQ425 are a little quieter aswell, though under half the weight so it's excusable.
If you have the volume with 1 440 per side but use 2 per side for coverage then 2 425's per side will be ok, if you find you need the volume of 2 440's per side for your gigs for 700 people..... it's too loud

So to conclude. Don't go from 8 small boxes to 8 or 12 massive heavy boxes, to gain nothing but more back ache and a need for a bigger van.
Don't expect you to increase the sound quality of your TQ boxes, not matter what you spend. I'm not saying they're the best sounding boxes out there, just that you get alot of sound for your box on stick. Something that anyones 12+1 box isn't going to match in volume, and most likely not in quality at any competitive volume.
Rob