Another vote for "do it" For a number of years I ran a Kenwood 2m all-mode for CW & SSB into a Mirage 160w amp into an M2 11-element beam at 45 feet. The amp very often made the difference between making the contact and not making the contact. Dave W7UUU
Yeah, it's a dB thing. 25W -> 100W: 6 dB 100W -> 160W: 2 dB The extra 2 dB is worth it when you're trying to work a signal that's 1 dB over the noise. But the 6 dB really helps. Those who are really seriously into VHF work often spend serious $ for a 0.5 dB improvement. Back in the 70s-80s, I was guilty of that, myself. I'd spend $200+ and several hours of work to replace my 1/2" hardline with 7/8" hardline on 2 meters, and the resultant benefit was literally about 1/2 dB on TX and 1/2 dB on RX, so total station improvement 1 dB. But I was a bit nuts, and so are a lot of weak-signal VHF-UHFers. HF can spoil us. I can lay 50' of hookup wire on the ground here and tune across 40 meters and hear 100 signals just fine. More like a thousand if there's a contest.
At VHF height is King! I'd go up to Mt Equinox at 3800 ft and work stuff with 10 watts that nobody else could work unless they were on a similar location, like Mount Greylock to the South. Yes, we could easily see each other's mountains! But, it took some technical skill to bring a station that wouldn't be clobbered by the 150 transmitters at the summit. I had a booming signal if I ran an amp. What made it special was that I was so much higher than the surrounding terrain. Zak W1VT
Going from 25 Watts (but isn't the TS-711 only 10 watts???) to 100 Watts IS a decent increase; going the extra power to 160 Watts may or may or may not be helpful. The REAL improvement (in your radio and/or antenna) is if you can hear them, but they can't hear you. If you can't reasonably hear them, increasing YOUR power just causes more QRM.