the performance may be variable from provider to provider, but I cannot really give you a direct answer.
Variables include the following.
Proximity of POP to exchange used by the backhaul carrier.
Congestion by the carrier/isp.
Possible congestion at the exchange (SVLAN)
ISP A may be great in AREA B and at same time ISP B may have problems in AREA B, but ISP A may have problems in AREA A and ISP B is great in AREA A.
The proximity of POP will only affect base latency and potential ramp up speeds, but not maximum speeds.
Plusnet mostly now use their own MSILS on BT wholesale, likewise BT retail also do.
Isps like AAISP and ZEN when using BT wholesale backhaul use shared MSILS.
Isps like sky and talktalk have their own backhaul so bypass BT wholesale.
Then there is another variable which is dependent on if you have 20CN or 21CN adsl services.
The short answer is you wont know till you try the new isp, some isp's are perhaps more likely to have issues than others, usually lower priced isp's.
Also with ADSL if you goto a provider with its own backhaul such as sky or talktalk it may affect your modem sync speed for better or worse as they use their own DSLAM's.
If you was happy with what talktalk provided, then its probably prudent to switch back if you leaving plusnet.