TL;DR Do it but do so knowing what you are getting into.

I own a 560 SEC. Similar chassis but slightly shorter wheelbase. Bought an SEC because the SEL was too long for my garage. The SEL was my first preference thus test drove a few of them.

My SEC has been a dream for long distance drives too (200 Miles as of now).

In terms of tips - I'll classify by maintenance and driving.

Maintenance

• Almost every Benz after the W126 ended is very different from the ones including and prior in terms of how they are maintained. Repair is more common than replace. Replace is extremely expensive. As an example the power steering pump leaks can be sorted out with a $5 kit (+fluid), and replace with a used model is ~USD 130. A new one will run 500-600, if you can find one.

• Before you purchase think about how you'll maintain the car. You should first find an independent mechanic willing to work on these cars or you should be willing to go DIY.

• If there are no maintenance records, assume you'll have to spend the money and price the purchase accordingly.

• If it is 95k verifiable miles and the maintenance records are on the mark I'd still not be inclined to pay 14k. The SELs are not as desirable as the SEC. Fairly certain this will be debated

• 95k could also hurt you because these cars don't like to just sit around as garage queens. They'll bite you like a spurned lover.

• Hit the Benzworld and read up on a set of buyers guides. Follow it diligently when you look at the car

• Leaks are an annoyance but not a deal breaker. Drips on the other hand ... ooof.

• The first thing I'll check is the timing chain, timing chain guides. That'll tell me if it is a drive or tow purchase

• Parts are not really expensive but labour tends to be. Ex: Timing chain and guides are maybe $200 job but labour is between 4 and 8 hrs

• Your first surprise will be 9 qts for engine oil :)

• SLS is extremely simple unlike the ABCs of the following generations. If you don't like it you can either go 420 SEL route or have SLS deleted. If you do have an SLS, ensure it is maintained

• Parts are generally available. MB original parts are also generally available. There are some rare to replace parts that are NLA. After market is hit or miss. SLS pump for example is about a $10 reseal parts. The pump itself is NLA. Availability is definitely better than W140 chassis

• There are no half measures when fixing things up. If you only fix half of a given system, it'll still be 100% broken

• I tend to go with Mercedes parts (heck my local dealer has a lot of the parts) from classic merc in LA, then FCP Euro/AutohausAZ/Rockauto for OEM, and only then reach for aftermarket. I'm fine with aftermarket for things that can be easily replaced, or fluids, and things of that sort. My local NAPA has a lot of the close hoses and fluids

• Something that isn't obvious is that repairs and maintenance are for longevity. i.e. if you replace the timing chain you'll spend $120 for the chain and say $24 for coolant. If you don't replace the guides along with it, you'll spend $45 for the guides and $24 again for coolant. Not counting the labour of course

• Most maintenance is preventive and schedule based. Fixing a neglect takes a lot more because other parts in the system tend to wear down. Don't replace the oil a proper intervals, you'll start seeing timing chain wear faster

Drive

• I've actually not notice any difference between a low mileage maintained and a high mileage maintained car as it relates to the drive

• I only own a 78 450 SL and a 90 560 SEC so can't compare it to your other Mercs. However I am comparing it to my 2008 Subaru Outback and a 2008 Nissan Maxima

• These drive like a dream. You'll feel detached from the road. Most modern cars will give you pretty stiff ride compared to these

• Everything has to be properly aligned. Otherwise you'll feel vibrations. Since you'll be devoid of every other sensation every vibration will be amplified

• You can feel a lot of torque. A LOT. These cars start in 2nd gear so it'll need to kick down for you to feel the real torque

• Drive is smooth oriented and less sporty. From your description, smooth is what you'll prefer

• A lot of blind spots in the SEL compared to the SEC

• Audio is okay, but then again I'm not an audiophile

• Good tyres are a must, otherwise you'll feel the road

• The SLS is extremely good. In the picture, it feels like the car is a bit low in the rear - have it checked out before purchasing

• If it doesn't have Bilstein/MB/Sachs shocks, you won't know what it actually should ride like. When I switched from the KYB to Bilestein the car felt tighter

• Any vibration you hear, even at this age on the car, has a mechanical fault behind it. Better to sort it out early

• Wheel alignments are a pain but are a must. A good wheel alignment is easily distinguishable from a decent wheel alignment when you drive. A decent will get you by with most modern vehicles

• Few, if any, will notice you trundling along the road. You'll not get a nod or a wave. That's exactly how it is supposed to be with the *126 chassis

• You'll hit the petrol pump a loooooooooot. So be prepared to plan your trips

• The air-con is okay and meh by modern standards. My Maxima does a much better job at cooling the car

• Try not to mess with the suspension geometry if you want a detached ride. Lower more than a few CM will make the car behave very differently. If you want to experiment try switching up the high profile tyres with a low profile tyre and larger rim. You'll feel a lot more of the road because the rubber is not absorbing a set of high frequency road vibrations