Myself I own a .40 size DP Ultimate, as well as 1/3rd GP Christen eagle.
Here is my take on all of these planes:
DP Ultimate - Awesome plane and even in the 1.20 size it only gets better. I have heard of some people putting a gas engine in this plane. Suitable gas engines would be an RCS 1.40, Roto 25, or even an MVVS. I would choose your engine wisely and do not just overlook this area. Your engine is what will be pulling your model around and putting it through its paces. Get something reliable.
Now on the Ultimate, it will knife edge very easily. It will flat spin like a dream. Torque rolls are no problem. So long as you keep it light landing is cake. Ultimates also like to fly a little fast so you may need to get used to that.
Cermark Pitts - Another winner as far as I am concerned. Never owned one myself, but it is also designed by Dave Patrick. I have read a review of people using both the Roto 25, and a modified Zenoah G26. From what I understand the modified G 26 will allow you to hang it from the prop a little. You may have to put some time in this bird to get the ailerons working right from what I have read.
BME Challenger - With a BME 50 the thing seems to fly awesome! I would suspect a DA 50, ZDZ 50 would give you the same results. You have a larger airframe with this bird, and more wing area. This would allow easier setup for smoke and you probably could get away with a heavier engine, but I would not recommend it. You can see the plane fly on BME's website. Does some basic hovering.
Price is a big thing you must consider. The BME Challenger will probably be the most expensive overall. Flying a gas engine however means much cheaper overall operating costs vs. glow on say a YS 1.40 for the DP Ultimate. Also consider servos and the like. You wont get away with weak servos in any of these planes. I would recommend something close to 90oz of torque at least and metal gears as well. My economy setup for my GP Christen eagle is HS645mg (133oz of torque at 6 v.) for servos. Although lighter and digital would be best.
If flying 3D stuff is what you plan on doing, then I would go with either the DP Ultimate or the BME Challenger. I think both would make you very happy. If you want just acrobatics, then the Cermark Pitts would fit the bill. Now I know someone out there will say the Cermark is the way to go, but this is my opinion.
I have actually seen both the DP Ultimate .40 and 1.20 size do 3D. From the forums on here and the BME website I have seen the Challenger do some neat 3D (although not all that crazy). Biplanes will need some mixing to fly with no tendancies, so I recommend a computer radio to handle that.
Whatever way you decide to go, plan out your plane first. Start with the airframe, then consider a power source. Choose your servos wisely and dont get cheap there either. Dont want to loose a nice plane you just put close to a $1k in to servo failure.
If you have any other questions I would be happy to help. I also have another NIB .40 size DP Ultimate I am selling, but it sounds like you want the bigger ones. The bigger they are the better they do fly
My choice of the lot would be either the DP Ultimate if you wanted a more affordable choice, or the BME Challenger if you wanted a plane built for gas. Speaking of which, the Challenger is on sale right now. Still a little pricey though in my opinion.
p.s. Wild Hare has a 50cc Ultimate on its way:
http://www.rcuniverse.com/forum/Utli...2720071/tm.htm
Tom from WH is probably the best guy out there for support as far as I am concerned. Will answer all your questions.