lets take into consideration of having the gt-2 with a small stomp switch and a boss pedal type with the big metal piece.It might not be that easy to switch fast enough.
as for needing 2 inputs on amp??
To the thread starter, you will have to understand how the looper/selector work and it will be clear that there is no need a 2 input amp
Using the boss line selector as an example(its a loop selector also, other than different name, it can do what you want and more). What you want to achieve is as below
loop A send(output)----->input of DS-1, Output of DS-1---->Loop A return(input)
Loop B send(output)---->input of gt-2, output of GT2----->Loop B return(input)
And your guitar cable out---->Normal input of the line selector, Normal output of line selector----->amp input
In one of the mode of the LS-2 which is what you want to do,
The guitar signal will go into loopA(Ds-1) and to the amp usually. If you want to switch from guitar signal to loopB(Gt-2) then to amp, just step on the pedal one time.
If the above still sound confusing, do google on loop selector, A/B switch etc.
As for the cost, nothing is too expensive when it can do what you want and make you play music...
imho and have fun