Can I swap from fixed rate to Rate adaptive & back again?

[#1]

Hi,
Because my line attenuation is horribly high (despite being within spitting distance of the exchange) I have a 1 Meg fixed rate connection.
Is it possible to change this to the normal Rate Adaptive connection - and swap back to 1Meg fixed rate if it all ends in tears?
To illustrate the problem, my stats are...
ADSL Link               Downstream Upstream
Connection Speed 1152 kbps 288 kbps
Line Attenuation   58.0 db 31.5 db
Noise Margin             11.6 db 21.0 db

[#2]

I think it is but you would need that confirming by a Plusnet staff member (probably on Monday).
Hopefully you'd get a sync speed of at least 2500kbps on maxDSL with IP Profile 2000kbps and throughput 1500kbps. Worth trying to see if the connection remains stable. Upstream sync should be 448kbps, with throughput around 360kbps.