I got my E100, first tier 10 for me, over the weekend; I believe there was a sale too, 10%? So it didn't quite cost me the full 6.1M. I had to play a few games just to load the tank with ammo and retrain my E75 crew to the E100. Then grind 64k XP for the 150mm gun and buy that... and ammo.
Now, I'm just playing for the 15k damage bonus and my money making mid-tier tanks that I do well in. I got several tanks that I'm done with and ready for the next tier but lack the coins. ISU-152 to Obj. 704. T29 to T32. Hummel to GW Panther. Stug IIIG to JagPz IV. I want to check out KV-2 and just 30k xp from IS-7.
FV304, I just can't get over how much fun that guy is.
Nice, congrats.
The E100 is a great tank. Maybe not the top Tier X, but it is solid. Can be frustrating to play though until you get the hang of it. Remember that your ammo has horrible pen for a Tier X (speaking about the 150mm here, which you'll want to run), so weak spots and lower plate only. Nice alpha but slow reload so you want to pen every time you fire.
The armor is good, but flat in area, such as the front of the turret. So never point your turret at the enemy unless you are about to shoot. An angled turret will be very hard to pen by just about anyone, whereas there are a lot of things that can pen it if you are pointing right at them and the face is flat.
The KV-2 is one of my favorite tanks. What's also fun about that tank is that it doesn't care too much if it gets into a Tier VIII battle as it can still do a lot of damage (just have to be more careful not to get shot). There have been plenty of Tier VIII battles where I've been the top damage dealer.
I don't have an FV304 yet. It does look like a lot of fun from replays, but it is highly annoying to play against.