Re: Greys Streamflex XF2 10' 5wt.
Just my $.02...
I think it's too fast/stiff for czech-ing...
It is a great indicator nymphing rod, but in my opinion it is not a great Czech nymphing rod. I fished the 11ft #4 Streamflex and I felt it is too fast for handling lighter rigs with lighter tippet. If I am fishing a bigger river/bigger fish situation, I am using an 11ft #4 CZN. It is a softer rod than the Steamflex and does a better job at European style nymphing (again,my opinion). Before I selected the CZN, I fished the Streamflex, TFO, Echo Shadow in 4wt. Later I fished the Sage ESN and One, and concluded that my choice was right for my budget. The ESN is sweet, but I can't afford $700 for a specialized rod.
If it is not a big river-big fish scenario, I opt for 3wt rods. The Europeans frequently fish 2wt and 3wt rods while tight line nymphing (on the other side of the pond fishing is more technical, use of 6x-8x tippet is common, and the fish are not as large as here in USA).
Since the fly line is not contributing too much to the loading of the rod (you only use a couple ft, if at all; sometimes the fly line doesn't leave the reel and you are using the leader only), you should be able to "load" the rod with the flick of your wrist to be able to control where your rig goes (accuracy). Another aspect is not breaking off the light tippet on the hook set, since you are fishing at very short range.
Don't take me wrong, it's a great rod, but in 5wt I feel it is too 'heavy".
I hope it works out well for you! Give us some feedback after you fish it.