if you're talking 8ms ISO response time vs 5ms ISO response time (like i think you are) on same technology panels, then no, you won't notice much, if any, real difference in practice. The difference might come when you start looking at screens with RTC / overdrive technologies where response times are listed as "G2G" figures....also when you go to other technologies other than TN Film, anything less than about 12ms in the spec would indicate RTC is being used, and so will vary again compared with TN Film panels.
Rough guide and time line for you:
- TN Film / non overdriven panels = 16ms, 12ms, 8ms, 5ms - all ISO response times, all pretty comparable in practice
- TN Film with RTC / overdrive panels = anything quoted with a response time less than 5ms, and anything listed as "G2G"....4ms G2G, 3ms G2G and 2ms G2G all common now, and again all comparable with one another in practice. These overdriven TN Film panels are arguably the fastest in the market in practice and normally the choice for gaming displays.
- PVA panels / non overdriven = limited to 12ms response time as lowest figure, rare nowadays, certainly no new models with them now. Pretty slow in practice and slower than all the 16/12/8/5 TN Film models, depsite their use of the "12ms" figure
- PVA panels with RTC = first gen was listed as 8ms G2G and showed no real improvement in practice compared with the non overdriven gen before it. Samsung then updated to their 6ms G2G rated gen which DID show some good improvement thanks to the RTC being used. 6ms G2G is current limit on PVA / S-PVA panels for response time, and responsiveness is pretty much comparable to 5ms TN Film gen and 8ms G2G P-MVA gen (see next bit).
- MVA panels without RTC = limited pretty much to 16ms as a minimum quoted response time. Again, very slow in practice, certainly behind TN Film panels with similar quoted figures. very rare, certainly no new models with them now
- MVA panels with RTC = most are listed as 8ms G2G, application of overdrive was very effective, comparable to Samsung's second attempt which formed their 6ms rated gen of PVA panels. 8ms G2G MVA panels comparable also to 8ms/5ms TN Film models.
- IPS panels without RTC = again limited to 16ms as min figure in specs, very rare now (note: ignore the Dell 2007WFP / 2007FP models here, they are actually 8ms G2G). Very slow in practice like the non overdriven PVA/MVA panels
- IPS panels with RTC = most are listed as either 8ms G2G or 6ms G2G, marked improvement thanks to overdrive, and some are even considered quite comparable to the fastest overdriven TN Film panels. overdriven IPS tend to be on par, or faster than the 6ms G2G PVA and 8ms G2G MVA panels
Hope that helps a bit as a guide...