Trying decide which motor to get between these 2. I hear great things about both. Has anyone tested both of these? If so, how would you compare them as far as power and runtime.

I did test my BTT from last year togheter with L7T5 on sunday. I think the T5 is the same as the BTT at bottom end But, the T5 revs alot higher than my BTT. Both tested with 2096 pipe and 41001 header.
I thnk the BTT would have perfered a longer header with the 2096 pipe.

Yep, but he is not asking about a btt but a keep off.
I have a plus 4btts and I hated it, no torque, no speed, very flat engine.
I now tested a keep off 4 and even tho they share specs, it is a completely different engine, torque is now present, speed is there and the engine is exiting to drive, plus it idles like a dream, I would rather get the keep off 4 but as I always say, this is only my opinion.

Piston/Sleeve/Rod - same part number
Crankshaft - same part number

So no, it's not "completely different".. Same engine, different bearings.

Seems like you had some mighty big placebo.

Bearings and case not same, only That makes a huge difference! but again, you talk about the btt, fine with me, but you never tried the keep off 4, so in fact you can not really compare the two....
Why on earth do you think That nova made the keep off 4 if it is not any different from the btt, just for the fun of having two same engines with a different name?

What pipe and header do u use?

Because people always want the latest and greatest. Also, Nova just loves to keep coming out with specialized bearings so you have to buy their super expensive ones instead of some cheap aftermarket ones. I bet they make more money selling one bearing than they do two engines.

All manufacturers do this. They will make some very minor changes, slap a new name on it and market it as the latest, greatest, bestest thing the world has ever seen despite the fact that it is at best only marginally better than the previous one. Eventually someone in the R&D comes up with something good and we get an all new product, which will then be marginally developed over the next few years.

The bottom line is that there is very little performance difference between a top of the line motor today and one from twelve years ago. An original P5 or WS7 or comparable motor is just as capable of winning today as anything else on the market.

The one I tested(keepoff 4) was with 41001 header and a 9901 pipe the one just with reinforced stinger. The combo was pretty good and we made around 9min pits at race pace.

I agree and disagree with you, twelve years ago a race engine was over powerful compared to today engines, they used way more fuel and this magical ten minutes pit stops was unreachable. today engines are in a way more civilized have a easier tune and are more of a power under control way of use.
Innovation are not always a big step at a time or otherwise we would already be driving nuclear powered rc cars with a 2 years autonomy.sometimes it might take a bearing, an another passage for fuel just modified and so on to make an average engine better! Still OS will name it speed 2 and novarossi will give it a new name from 4btt to keepoff. This is the way we go forward and company's stay alive.
On the other hand their rear bearings costing 45€ in steal and up to 75€ in ceramic That is limit scandalous, when you know how much they do in fact pay them, the margin is really high, also a engine bought in spare parts would cost 3 times what it does cost in the box and assembled.
As you talk about the famous ws7 from rb the very one Kanai won his world title with, at That istime he was pitting around 7 minutes and today in a race like a world championship where they drive an hour he would have done 8 stops where today engine would only do 6 stops, and That to me is an evolution.

I didn't watch the race but from what I read the winner of the Euros was doing 7:30 or so stops.

Yes some tracks you see 10 min or more stops, some tracks you see 7 min stops. That being said, yes we get better mileage today than we used to but most of that is from the pipes. On a track that people often go 10 on today, give me a NIB 12 year old WS7, let me put a modern pipe on it like a 2058 or 2096, a 6mm venturi, modern fuel and a well set-up modern clutch and I will go 10 too. That same motor with a period 9886 pipe, 8mm venturi, etc. and you might get 8.

I know this is an old post and before you crucify me, hear me out. I am the proud owner of a couple lucky 7's L7T5's along with a few other of this period. Does the same hold true to the engines in today's standard or have we had the something good from r&d and these engines are "dinosaurs" I am asking as I am curious if it is worth sending these engines off for "work"

I still run my BTT with 9901 pipe... That engine is still competitive..